I don't think Acrobat is doing this. (And just as well, there have not been fixes to version 8 for many years).
I say this simply because it seems to be a brand new problem, and it seems to be affecting multiple versions. Other people have lost title bar and menu, but don't have this grey space because later versions of Acrobat have a different window design.
That said, I don't have many other suggestions except to try and find the culprit.
You can try Alt - (alt hyphen) to see if a menu appears and select Maximize or Resize (resize will use the keyboard).