White Hart
One problem I've seen with Adobe products, like Acrobat, is that they sometimes put up a pop-up window with a dialogue box, but the box isn't set to be the front window & ends up being hidden behind whatever else is working on your PC.
If you've had enough fo waiting and have then started to shut down various programs you'll find the box after quite a few things have closed.
If I find Acrobat is taking a long time to do something, I tend to minimise everything in sight and look for the dialog box. This isn't fool proof, sometimes Acrobat just get's it proverbial knickers in a twist, but I reckon on about 9 times out of 10 I find the box hidden away behind another window.