Hello, I recently faced exactly the same issue. The problem was in bglman_fbeam.dat file of zero length in FS Modules\ folder. I've deleted it and everything worked like charm.
That's why you should always run the updated Addon manager for FS9 last: it removes those extra files which are not needed anymore and would have been created by older installers. The latest version surely does that, and has been online since May 7th, it's 1.9.2