I guess you have Win 7 Home, Professional is the upgraded version. Others have suggested different Readers, I have never had problems with Adobe Reader. I have Windows 7 Professional, and Adobe Reader 9 Version 9.4.5. Can you open Adobe Reader just by clicking the Icon. If you can't and get the same message, it's a bad install. Uninstall Adobe Reader, and make sure it uninstalls completely. You have to go to the Adobe Web Site and get the Clean Uninstall Tool. Then get the latest Adobe Reader from their Web Site.