asking for serial number whenever I try to open a pdf document
All of a sudden, a Acrobat XI Standard window pops up whenever I try to open a pdf. I put in the serial number and get another window that says Serial Number Upgrade saying the "Serial Number you provided is value, but a qualifying product could not be found on this computer. To use this serial number, you must own one of these qualifying products. Please choose one of these qualifying products. Please shoose the one you own and enter its serial number". None of the product options are for Adobe Acrobat XI Standard, which is the product I purchased/am trying to use.
