Again, be sure you remove THESE folders, when FSX is not running, of course, maybe after a Windows restart:
C:\ProgramData\Virtuali\Couatl ( NOT %APPDATA%\Virtuali!! )
C:\ProgramData\Microsoft\FSX\SceneryIndexes
restart FSX, wait for both FSX and GSX caches to regenerate and, if it's still giving you errors, enable Logging in the Troubleshooting section of the GSX Settings menu, and post your Couatl.LOG file.