I installed .Net Framework 3.0 and 3.5 but it didn't help.
Do you by any chance know of a specific service that should be running in order to launch the viewer? Or maybe is there a log that would be recording the cause of the error?

You didn't say if your account has administrator level? Also, try running ModelViewer just by double-clicking on the .exe and see what it says. Obviously it won't do anything useful started that way but it might help to narrow down whether it's a problem with what TT3 is sending it, or with modelviewer itself.

It's the only account so I assume it can only be administrator. And nope, it doesn't work when I try to launch the viewer as a stand alone, I get the usual error message.

If I run it direct, it sort of runs and closes silently as I don't have a mesh for it to open. The fact you;re getting an error message almost certainly means you don't have some prerequisite. But what could it be? I can't think. DirectX? something like that? Nvidia utilities?

Your not editing or using STORE stuff are you?
Few plugins will not work on those.(like the GEOM viewer)

Well he got an error just trying to run it direct, it should have just died silently in that situation. Getting the error from that would imply there is a systemic incompatibility with the tool.

Nope, I cloned base game stuff.

Ok, so I installed a new copy of Windows Xp on a laptop, got the drivers, DirectX, and .Net Framework 4 - just in case something would be interfering on my main computer. It didn't work, I get the same error.

I'm installing Windows 7 at the moment. Maybe I get lucky with this one.

Ah, I am not sure if anyone ever tried the tool with xp! Maybe that is the problem after all.

I get an error if I run ModelViewer directly, too; and I don't think this is unusual as it is not meant to be run on its own. When expanded, this is what Problem Details panel show. A snippet, anyway.

But it runs fine in both
- s3pe, am on
Front-end Distribution: 13-0129-1554
Library Distribution: 13-0129-1554
- TT3 is on v0.56 and
- I have Windows 7 SP1.

And I re-iterate cmomoney's question, with some amendments:
How do you have (the tools) installed?
The exe installer or the zip versions? And the s3pi wrappers themselves?

I have them from the zip versions; and I don't have them in my Program Files but in a custom path.
And the wrappers are unzipped into each S3PE and TT3; because as Inge have warned us again and again, not to mix the Helpers and wrappers with the s3pe/s3oc files themselves as they are using different versions of the s3pi libraries.
And the ModelViewer (in the Tools menu) is then hooked up to its own subfolder under the TT3 folder. TT3 does not know of s3pe's existence, wrappers in one does not know of wrappers of the other, and vice versa.

Because you may have messed the installation and uninstallation, I suggest when you next uninstall, to do a Full Cleanup with CCleaner which would clean all the leftover stuff in your %appdata%. But that means, you have to setup all you gamefolders over again (for s3oc).
As an added precaution, in case the issue lies with a bad browser cache, exit your 'net browser and closed down Windows Explorer before you run CCleaner. And then, clear up histories, caches and cookies.

Ideally, if you followed a tutorial and have problems following that tutorial, we ask that you post your questions in said tutorial. Else, we'll be inundated with questions about all tutorials under the metaphorical Sims 3-Sun. But since, we're now well into the 2nd page, I'll just let this run its course...
Lucky the folks that hang @simlogical are the same folks here, though.

Now it feels that the harder I try the worse things get. *sighs*

I formatted my laptop, installed Windows 7, drivers, .Net Framework 4, Sims 3 (just the basic), S3OC and s3pe. Unzipped the Texture Tweaker and s3piwrappers-r214, both are on the desktop, in separate folders.
Cloned a basic chair, then launched the Texture Tweaker and set the location of the Model Viewer. Opened the package and clicked 3d view. And... I get a different error.

I don't know if this makes any sense, I paste it just in case:

See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.ArgumentNullException: Value cannot be null.
Parameter name: image
at System.Drawing.Graphics.DrawImage(Image image, Int32 x, Int32 y, Int32 width, Int32 height)
at s3ow.MangledPics.ResizeBitmap(Bitmap b, Int32 nWidth, Int32 nHeight)
at s3ow.s3owMainForm.FullCompositeBlended(String dirtOverlay)
at s3ow.s3owMainForm.CompositeModelPreview(String dirtoverlay)
at s3ow.s3owMainForm.button_3D_Click(Object sender, EventArgs e)
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)


************** Loaded Assemblies **************
mscorlib
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 (RTMRel.030319-0100)
CodeBase: file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/mscorlib.dll
----------------------------------------
TextureTweaker3
Assembly Version: 1.0.0.0
Win32 Version: 1.0.0.0
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/TextureTweaker3.exe
----------------------------------------
System.Windows.Forms
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Windows.Forms/v4.0_4.0.0.0__b77a5c561934e089/System.Windows.Forms.dll
----------------------------------------
System.Drawing
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Drawing/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
----------------------------------------
System
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System/v4.0_4.0.0.0__b77a5c561934e089/System.dll
----------------------------------------
s3pi.Interfaces
Assembly Version: 1301.29.922.16885
Win32 Version: 1301.29.922.16885
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.Interfaces.DLL
----------------------------------------
s3pi.NameMapResource
Assembly Version: 1301.29.922.16886
Win32 Version: 1301.29.922.16886
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.NameMapResource.DLL
----------------------------------------
s3pi.CatalogResource
Assembly Version: 1301.29.922.16886
Win32 Version: 1301.29.922.16886
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.CatalogResource.DLL
----------------------------------------
DDSPanel
Assembly Version: 1301.29.922.16884
Win32 Version: 1301.29.922.16884
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/DDSPanel.DLL
----------------------------------------
System.Core
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Core/v4.0_4.0.0.0__b77a5c561934e089/System.Core.dll
----------------------------------------
TextureTweaker3.resources
Assembly Version: 1.0.0.0
Win32 Version: 1.0.0.0
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/en-US/TextureTweaker3.resources.DLL
----------------------------------------
System.Configuration
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 (RTMRel.030319-0100)
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Configuration/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Configuration.dll
----------------------------------------
System.Xml
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Xml/v4.0_4.0.0.0__b77a5c561934e089/System.Xml.dll
----------------------------------------
System.Xml.Linq
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.1 built by: RTMRel
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Xml.Linq/v4.0_4.0.0.0__b77a5c561934e089/System.Xml.Linq.dll
----------------------------------------
s3pi.TextResource
Assembly Version: 1301.29.922.16887
Win32 Version: 1301.29.922.16887
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.TextResource.DLL
----------------------------------------
s3pi.WrapperDealer
Assembly Version: 1301.29.922.16886
Win32 Version: 1301.29.922.16886
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.WrapperDealer.DLL
----------------------------------------
s3pi.Package
Assembly Version: 1301.29.922.16885
Win32 Version: 1301.29.922.16885
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.Package.DLL
----------------------------------------
s3pi.Settings
Assembly Version: 1301.29.922.16884
Win32 Version: 1301.29.922.16884
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.Settings.DLL
----------------------------------------
System.Custom
Assembly Version: 1301.29.922.16884
Win32 Version: 1301.29.922.16884
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/System.Custom.DLL
----------------------------------------
s3pi.CustomForms
Assembly Version: 1301.29.922.16885
Win32 Version: 1301.29.922.16885
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.CustomForms.DLL
----------------------------------------
s3pi.DefaultResource
Assembly Version: 1301.29.922.16886
Win32 Version: 1301.29.922.16886
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.DefaultResource.DLL
----------------------------------------
s3pi.Extensions
Assembly Version: 1301.29.922.16886
Win32 Version: 1301.29.922.16886
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.Extensions.DLL
----------------------------------------
s3pi.Filetable
Assembly Version: 1301.29.922.16889
Win32 Version: 1301.29.922.16889
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.Filetable.DLL
----------------------------------------
s3pi.GenericRCOLResource
Assembly Version: 1301.29.922.16886
Win32 Version: 1301.29.922.16886
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.GenericRCOLResource.DLL
----------------------------------------
s3pi.MeshChunks
Assembly Version: 1301.29.922.16888
Win32 Version: 1301.29.922.16888
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.MeshChunks.DLL
----------------------------------------
s3pi.RCOLChunks
Assembly Version: 1301.29.922.16886
Win32 Version: 1301.29.922.16886
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.RCOLChunks.DLL
----------------------------------------
s3pi.ObjKeyResource
Assembly Version: 1301.29.922.16887
Win32 Version: 1301.29.922.16887
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.ObjKeyResource.DLL
----------------------------------------
s3pi.TxtcResource
Assembly Version: 1301.29.922.16887
Win32 Version: 1301.29.922.16887
CodeBase: file:///C:/Users/Nynaeve/Desktop/Texture%20tweaker/s3pi.TxtcResource.DLL
----------------------------------------

************** JIT Debugging **************
To enable just-in-time (JIT) debugging, the .config file for this
application or computer (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging
enabled.

For example:

<configuration>
<system.windows.forms jitDebugging="true" />
</configuration>

When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.

And the link to a screenshot:
http://postimage.org/image/ay1xybff3/

Katmosis please send me the package you were attempting to edit when this latest problem occurred. I want it as is, not a fresh copy please. You can send to [email protected] or attach here or whatever

Can you still reproduce the Model Viewer error running it standalone? If so, could you also go to My Computer->(Context Menu)Manage->System Tools->Event Viewer->Windows Logs->Application and find the error event -- the source will be ".Net Runtime" and the time will be the time you got the error. You might want to clear the log before reproducing the error to make it easier to find.

Once you've found it, choose Action->Copy->Details as Text and post them.

After I posted the error log I decided to clone a few more objects and hope for a miracle. I can't explain how, but it happened! IT'S WORKING!
(maybe I didn't restart after installing things)
Thank you guys so much, I would have given up long ago if it wasn't for your kindness. I'm so happy I wish I could hug you all. :lovestruc