FDC runs independent of FS9 meaning FS9 doesn't control it's stability. Yes FDC runs in tandem with FS9 and I'd give you some credence on a reinstall if FDC crashed only after FS9 was already running but FDC crashes with or without FS9 running. This problem actually has nothing to do with FS9 at this point. Yes the initial problem was related but the resulting issue is an application that won't start whether FS9 is running or not. With nothing else running on my system launching FDC results in a fault right after the splash screen. I can't get to the main menu with FDC anymore...
I like Dave March's approach because not all problems (in fact very few problems) require a complete reinstall of Windows and/or FS9. That's bad support advice when nothing else is faulting on one's system. Your talking quadruple the work reinstalling FS9 when this problem is independent of FS9. I'd go through all that work and get the same results from FDC (I guess next would be to reinstall Windows)... This is simple faulting file issue that can be easily resolved with a debugger file for FDC.