Since it seems that none of us have ever experienced this, you're left with too many unknown possibilities and no quick answer. Start over - rename the current Combat Flight Simulator 2 folder to Combat Flight Simulator 2.X and reinstall the sim. Try the same scenario in the fresh install. If all goes well, copy whatever you want to save from the old into the new and delete the old completely.
If you first un-install through Windows ADD/REMOVE, you will lose any mods you've put into the current install. By renaming the current folder you save these mods to use in the fresh install.