There's several factors that I believe could factor into your problem:
- Fleet Command being a 32-bit program, could have an issue with the way Windows 7 x64 is addressing memory.
- Windows 95/98 or Windows XP Compatibility Mode might not be engaged
- Conflict with outdated or even updated graphics drivers. At that, is your graphics card made by Nvidia, ATI or a third party?
- Are you running at a weird resolution that Fleet Command could have a problem going to 640x480 from? (It can address up to 1024x768)
- If you have Windows 7 Professional or Ultimate, have you considered running Fleet Command in its special Windows XP virtualization mode?