Every time I open a PDF file in Internet Explorer 7, I keep seeing a message stating that I need to go to the "manage add-ons" option in IE and select enable Adobe. The problem is that the Adobe add-on is already enabled, yet I keep getting this message. What do I have to do to fix this?

Have you tried disabling it, then re-enabling it? Other than that I'd say uninstall acrobat and reinstall it. That should fix the problem if it is related to the installation and maybe it being corrupt?

Also,in Adobe Reader, edit menu/preferences/internet make sure 'display pdf in browser' is checked.

That's a problem I had *once*, and that was after updating Acrobat Reader to the latest version. However, I did *not* have that issue after changing from IE 7 to IE8 beta 1. Figure that.