part color

Really big parts will do this. If your parts are about 800mb, you'll just have to put up with them grey. I tried all sorts to get round this and couldn't. If your parts are a more sensible size, I don't know what's going on. Can you load parts in different colours from other machines and view them in these colours? That at least will suggest your graphics card is okay. If not, check your card compatibility and drivers, for a start.

I'm working with small parts and assemblies. I think I have same broken dll in my system directory, but I don't know which are.

I think your best step is to reinstall xp, run liveupdate, and then reinstall Pro.

Make sure you have backups of your data before you do this, and test them.