I'm sorry, but those solution (try all of them, including the Windows reboot, which might be important) always fix the problem. Unless you have another product, like an antivirus that corrupted the file.
You can check the bglmanx.dll file in the FSX root folder: if the "Digital Signature" under the "Properties" page, reports as valid, then the file is ok. If it's invalid, it means a product on your system has corrupted it, which could be either an antivirus or a real virus.
If the file is ok, then the problem (assuming it doesn't go away by following my previous solutions to the letter) is likely you have a problem with some of your system libraries, most likely the VC++ 2005 runtimes. In this case, repairing the FSX SP2 (or Acceleration) install, might fix the problem.