Directx 10 graphics problem!!

I have an M14x R2 with a Nvidia Geforce GT650m. The problem I have is that any game that runs on Directx 10 makes the graphics a complete mess in full screen mode (works ok in windowed mode). About a second after the game loads (the logo/intros) the graphics just become a complete mess - all kinds of weird bright colours and very pixelated. If I flick to windowed mode they are fine, then if I flick back they are ok for around a second again. I have downloaded the latest Dell drivers, I've tried the Nvidia website but there appears to be no drivers for my card on their site(!?), and I've downloaded the latest Directx drivers too. If the game runs on Directx 9 or 11 it works fine.

I'm at a complete loss.