GTA III Not Working :(

Hey guys,

I bought GTA III for my computer, and it's not working!

Ever time I click (in the game) to the right side of the screen, the bloody thing minimizes!

I thought it could be my new HUGE LCD screen I got for my bday (ahem), but it was tested at the shop, with a screen similar and it didn't do a thing.

I'm running Windows XP (tried the patch that's suggested for XP users, didn't work), P4 2GB, 1GB Memory.

The shop said it's my computer and refused to exchange it.

HELP!!!

L_S