Delta,
You are operating at the minimum system specs in video memory for the game (64MB). It sounds like you are running out of video memory.
I would suggest the following:
[*]Ensure that every unneccessary process is closed[*]Make sure the display is set to 16-bit color.[*]If the problem persists, try switching from "picture" icons to "NATO symbol" icons for vehicles. This uses much less video memory.
Let me know if this doesn't solve the problem. You can contact me at:
techsupport@prosimco.com