This happened to me the first time today. I attempted a reinstall/repair of the Flighttoolkit without success.
I also attempted a system restore to a few days ago when the non-GFWL Flighttoolkit modified Flight was working fine but before a Windows update but again no success.
I just found Flight a few weeks ago and appreciate stonelance's (and others') efforts to keep this enjoyable program available. Thank You!
I don't have the time available to dedicate to a hard-core sim system but love Flight!