Try to cascade all of the windows. It's possible FM picked up some coordinates that are off-screen.
In either / both cases are multiple monitors involved? The fact that you are getting a login screen and then nothing makes me think it is opening off screen somehow.
Did it ever work right and then suddenly it is not?
I have the latest version of Windows 8 with all the updates as of this morning and FileMaker Pro 14.0.4 launches and works fine for me.
I agree it is acting like there is a 2nd monitor
However neither has one. The computer this happen on this morning, when she left work yesterday all was well.
When she came in the AM this issued happened
She had multiple windows updates from overnight, I removed them all and restated. Issue still exist
What happens if you uninstall/reinstall FM?
I did that also. Problem remains.
try resetting all dialogs, it's in the preferences (Edit Menu)
I just spoke to the "Computer guy" that went to the 1st office that had this issue and he was able to fix it. He drilled down in to the task manager and the Filemaker setting had been altered to Minimize
He changed that to maximize and the problem was resolved.
Both user had a virus recently both had windows updates
One of these changed that setting!!