Huge Yellow Blocks! Help me *insert name here* you're my only hope!!

Okay, many people had the same problem with the game that I had, and last year no one could help us out. So I said, what the hell...maybe someone here NOW can help.

Here's the problem. I have an ATI Driver graphics card (I think) and in the game, several things are surrounded in yellow blocks. Everthing from the Pod Racers, to the spaces inbetween a droids hand. All the backround in some levels is like that too. Everythings incased.

I tried downloading the lastest drivers, but that only turned to boxes black..instead of yellow.

I also tried addative blending, and that didn't work either.

I have a Pentium 2 400 computer, so my PC is fairly new, and when I took it to my friends house, he only has a Pentium 300, and it was fast as hell on his, and all the graphics were fine...me...I have to turn all the details off so I can get a decent running speed...and it's still slow.

I know this is alot...but can anyone help me out? Any ideas..suggestions...whatever. Thanks.