The other day I manually installed the alkatraz scenery into my add on scenery folder.
Unknown to me, an entry was also somhow created in the main scenery folder by the install routine even though I expanded files to a temp folder.
This happend before I even activaed the scenery through the add on scenery routine.
In FS9, you would get a "scenery configuration" error message to clue you in on the problem.
FSX however, just hung up on the splash screen.
It was only when I clicked on FSX in the "task bar" did the error messag appear.
Aparently error messages might be awaiting but only appear after doing what I described.
It this is the case, this is definately one for a patch!