I've been working with milkshape a lot that this never happened before.
when ever i import a .wso file that has 2 groups in, and go to the joints tab and press draw vertices with bone colors, milkshape always crashes. this doesnt happen with the mesh's other part ( the low quality one) just the high one. i tried a lot of different meshes, yet the same happenes. this started to happen when i re-installed my windows. i downloaded every thing that milkshape requires, and still nothing

so what i'm missing ?

thanks.

maybe update your videocarddrivers?

yep it needed to be updated, thanks for the help =) every thing is fine now