Adobe Reader stops responding on highlighting a scanned document

I need to report a bug, but the system is just awful for finding a way to do so. So, here it is:

When I'm using Adobe Reader to read a scanned document that does NOT have highlightable lines (that is, I use the highlighter tool to make horizontal/vertical highlight marks and the lines snap to straight lines), after some time (say, a couple pages of reading) the reader stops mid-highlight, a window pops up and disappears in a fraction of a second, and the Acrobat Reader window stops being active. However, there is nothing in front of it to close, so it's impossible to return to the window in which I was reading. So, I have to open up Task Manager and end the process and re-open my document again.

Please have this bug checked out or let me know if I need to explain it better.