Acrobat PDF files will not display in SimpleIndex, and when I exit the program it crashes.

This is a known compatibility issue between the browser plug-ins for Acrobat 6 (Full) and Acrobat 7 (Reader). When both programs are installed on the same machine, and automatic updates are applied, registration for the browser plug-in is corrupted.

This problem affects any application using the Acrobat browser plug-in, including Internet Explorer and other web browsers.

The short-term solution is to uninstall and re-install Acrobat 7. It is recommended you download the latest version from Adobe to prevent the problem from recurring when the next update is installed.

The long-term solution is to upgrade to Acrobat 7 Standard or Pro and uninstall Acrobat 6.