Wonder if anyone can shed some light on why FSX has begun crashing.
Been happily running FSX problem free for a year now and just recently installed Aerosoft's Balearic Islands X prior to this problem, incidentally it only happens on airfields in this package and would post my query on their website but I'm assured that it's a Windows Issue.
I can't tell you for sure but quite possible that the two games share a common file(-s) that can't service both games, or the FSX installation got corrupted when you installed Aerosoft's Balearic. I don't think it's a Windows issue.
1. Uninstall these two games, reboot, then try installing each separately and see if the issue persists.
2. Update DX and video/sound drivers
If no luck, contact technical support.