Where is the dialog box?

This has happened many times now and for different reason (not always doing the same thing). 

What is happening is that my Adobe Acrobat window changes size (out of full screen), blocks whatever was in the next full screen, and if I click on any part of the file, I get a "beep" sound as if a dialog box is open and you have to, say, click save. 

Sometimes this happens when I'm quitting the program. Sometimes this happens when I'm opening a new file (with the program already running). Sometimes this happens when I'm just saving a file. 

I've tried clicking "return" (to pretend I'm saving something) or "esc" (to exit what ever dialog box is blocking my use) with no results. I can move the window around the screen, but I cannot change its size or do anything else. If I click any of the menus at the top, all options are gray (you can't use them).

My solution has been to force quit, but this is getting out of hand. 

Any idea how to see that bloody dialog box? 

Thanks!