Which version of Acrobat are you using, on which operating system?
If a normal re-install does not fix a problem, I would try to uninstall, then run the "Cleaner" tool (http://labs.adobe.com/downloads/acrobatcleaner.html), and then install Acrobat again. The "Cleaner" removes any trace of Acrobat or Reader from your system. This means that if something got corrupted in the configuration, a simple uninstall will potentially not remove that corrupt configuration setting, but the Cleaner will.
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
http://www.khkonsulting.com