The problem it's likely caused by video memory card corruption, due to one of the following:
- A video driver bug. Update your video driver and reset it to default options.
- A FSX setting or tweak that shouldn't be applied. Reset your FSX.CFG to default, by removing the %APPDATA%\Microsoft\FSX\FSX.CFG file, then apply only the HIGHMEM=1 tweak (using the Addon Manager)