Ok, could you all try listing some specs? It is going to be tough to find a common thread if we have to play 20 questions to find out what systems you have. Probably should add what unit size setting you are using, as well as basic info about resolutions and game settings. For all we know you might all have the same vid card... or be running with minimal memory, etc.

This sounds like a lack of video texture memory or something like that. Having it happen in large vs. small battles suggests as much. Could be lack of system memory too. Or could be the drivers or BIOS settings.