I seem to get this error when opening PDF files from the internet with Acrobat Reader 8 but when I have the full version of Adobe Acrobat installed I can open them fine. Can anyone explain why or how this happens? Not everyone has the full version, does anyone have any suggestions about how to fix this so they can open in the reader. I have checked the preferences and open PDF file is checked as well.
It could be because you have both installed which is not a recommended nor supported setup.
My suggestion would be to uninstall both, run the Microsoft Installer Cleanup Utility to be sure everything is gone, then reinstall only one of those products.