I dont think we can help you anymore then, i have 1 last sugestion, this sugestion will help your computer overall too. Get service packs for ur computer if u havn't before, get directx(latest version) i believe the latest update of directx was in august, and frame network 3.5 if u dont have.
If this doesn't solve the issues then its the computer and i don't know any more options.
If this does work, plzz thank me.