I have a Windows XP Service pack 2 operating system. When I installed adobe 8.0 and try to open PDF files I get the following message "One or more Adobe PDF extensions are disabled. This may impact how PDF are displayed in Internet Exployer. Go to add ons in IE and enable add ons from Adobe. Restart IE." I did this and no adobe add ons were disabled. I checked with Microsoft and they suggested I check with Adobe.