I thank you for your assistance. I took your advice and did a system restore, but the problem could not be resolved.
I did a search in the Event Viewer and the results are as follows:-
Event ID: 11321
Product Adobe Reader 9.3--Error 1321. The Installer has insufficient previleges to modify the File C:\ProgramFiles\Adobe\Reader 9.0\Reader\plug-ins\Annotations\Stamps\Words.pdf.
Thank You All for Your Assistance.