I used to get the flashing areas on the campaign map problem...and after installing the newest drivers for the GPU (a GEFORCE 7600GS) and reinstalling direct x that problem hasnt re-occured yet...however, I get problems with the battlemap graphics (it seems mostly during day, rather than night battles) its a very similar flashing areas/lines problem...as well as there being areas on units (and buildings) that are completely see-through.
Any ideas? no tweaks to graphics settings seem to change it ( but night battles work?!) what NVIDIA drivers are other people running?

otherwise the system is a Pentium 4 2.5 gHz, 512 Meg ram, 11 Gig free hard disk space for the game. Could a lack of RAM cause this?