problem with screens

I have just had a Windows clean re-install carried out. Since re-installing FS2004, I have an odd problem. When I get to the 'select aircraft' screen, I get a black rectangle in the aircraft view screen. The rectangle occupies about a sixth of the aircraft view portion of the screen. Then, when I select 'fly now' the programme closes down. I have found that I can get round this problem by starting with the default aircraft, clicking to reduce the screen size, and then loading the aircraft of choice. I can then fly normally BUT, whenever I click on 'full screen', the programme shuts down. Can anyone offer any assistance please?