Graphics problem: flashing screen

[SirLance]

Ok, I just got a new computer and installed the sims 2 on it to see how well it would run. Well, it runs very fast and smooth but I have a problem where the screen will occasionally just flash. Now this is starting to get quite annoying because sometimes it will flash many times in succession. Does anyone know why this could be happening?

System specs:

Windows XP Pro
AMD Athlon 3200+ Venice 2000MHz (overclocked to a 4000)
Radeon X800 512MB PCI-e
160GB hard drive
Corsair XMS 1GB

I'm thinking it could be a driver issue, but I'm at university right now so I can't actually check, but I thought I'd try to get anyone's thoughts.