In the past couple of days whenever I close a pdf file that I’ve opened in Acrobat (11.0.03) I get a small grey smudge in the middle of the screen with a vertical line at the top of the grey area (see below). This grey area and the line go away when I click on the screen. The same grey smudge appears when I try to use the “Combine files into a single PDF” and this function doesn’t work. The same problem doesn’t occur when I open and close pdf files in Apple Preview. I tried deleting Acrobat and then reinstalling but the problem persists. I’m using OS 10.8.4 and have not done anything new to my system.
