yes alt-tab would fix the flashing graphics but it would still lock up now and again and need a hard reset.

I found city builders fix fixes that flashing and the lock ups, i've been playing for a couple of days now with no crash.

from the sounds of things on the forum the crash is to do with the vista and 8000 serires video cards. I never had a problem on xp.

Edit: seems its still crashing giving me a black screens now. So irratating

I have the same issue. I cannot play for more than a few minutes. I am running Vista 64 and am using 2 BFG GTX280s in SLI.

The problem may be in SLI mode, try to switch off one of the cards.

Shockingly...that fixed it. I created a single card profile for this game and it runs just fine. I have seen SO many posts on this in so many places and boards and no one has an answer. I would imagine that might fix it for a few people. Thanks.

I had this problem for months and thought it was a general problem with my video card. This also happened with Heroes 5. Screen would go black and lock machine completely causing hard reset. I noticed on both games that anisotropic filtering was maxed out. I turned down only this one setting to 2x and it solved the problem. I haven't noticed this with any other graphic intensive games so it may be something in these engines causing a problem with my nvidia card or the latest drivers. I really can't see much graphical difference now and have no more crashes. Hope this helps someone.

freezes
 

I have italian version (so i can only have 1.6.4 native version or 1.7 patch), with 1.6.4 che game crashes to desktop as soon as i enter the 3d map; with 1.7 it does work but freezes randomly when a dialog overlay appears. I've tried anything: citybuilder config, newsest vga drivers, 4:3 aspect ratio, lower settings...etc
It's always the same, random freezes. I have one of the firsts athlon x2 4400+ and a 8800gt.
I've played several hours (i'm level 8 ), but the freezes are getting worse, today it does always freeze after few minutes, i suppose the only chcance is a new patch.
:( it's so sad a game so good have such issues which definetly prevent me from being able to finish it