Does this qualify as a bug?

After a short time of play (my record without this error is about 50 mins) the screen turns to a grid of primary colors. The only way to fix this is to reboot. I can not toggle out. It's now happening so often the game is unplayable. Huff. Any suggestions?

Hi, my friend also has this problem. he has ATIcard 256mb. we were playing LAN for a few days perfectly no problems. we saved a LAN game after his first crash and now it crashes like every few miniutes when he joins.

all the civ interface goes in primary colours and he has to restart his machine. ive no idea what the problem is. mayb the save game when transfering? or perhaps the graphics driver. but the driver on his card is upto date