Scrambled graphics piccy - anyone seen this one?

[Wide_Arc]

I mentioned this in a previous post but didn't have a screeny at the time. This one is possibly only happening when graphics are set to higher end, though I can't be bothered to reboot Civ IV ten times to verify, to be perfectly honest. The same issue crops up when Stronghold2 is set to higher graphics.

Anyone seen this / have a view on likely culprits? (Apart from Take2's rubbish coders, obviously!)

http://www.chrisandsuz.homechoice.co.uk/totalrubbish.jpg

Specs:

P4 1.9Gig
512 RAM
420W Tagan PSU
GeForce 6600GT
MSI Mainboard w/ latest Bios and Drivers
Windows XP Home