We created a form in the demo version of Acrobat 8. Then tested filling in this form on a different computer using Acrobat 7 Professional. This caused all of the plug-ins to disappear. They are still installed on the computer, but do not show up in Acrobat. A reboot does not help. We also uninstalled and reinstalled all of the plug-ins.
Leonard Rosenthol
PDF Standards Architect
Adobe Systems