This almost sounds like a floating window disappearing behind another panel or all the panels closing at once leaving you with a blank UI like the one below. Although I doubt that the windows are all closed without asking to save first.

I have asked before and I will ask again, can you provide a screencap of your Pose Room?  Without this illustrated information, we cannot offer an adequate solution.  Do you know how to perform a screencap?  If the User Interface is becoming problematic, you can reset it back to Factory settings under General Preferences.