There is no application called "Adobe XI" - are you using "Adobe Acrobat XI" or "Adobe Reader XI"? On which operating system?
You may have to uninstall, then run the "cleaner" application (which you can find here: http://labs.adobe.com/downloads/acrobatcleaner.html) before you install the application again.
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...