TM7,
When you say you "reloaded" Adobe, do you install over top of the original installation? Or did you uninstall Adobe Reader, reboot the computer, and then re-install Adobe Reader 9.1 from here:
http://get.adobe.com/reader/otherversions/ Or you could try uninstall version 9.1, reboot the computer, and then install the older version of 8.1.3 that is available on that same webpage. Once you verify version 8.1.3 works, you can try upgrade to the new verions of 9.1.
It does sound like the installation is corrupt. I don't remember for sure with Vista, on XP you you can tell Windows which program to always use when you open a specific file type like .pdf files. On XP, you would right-click on the .pdf file, select Open with>Choose Program from the context menu that appears, select Adobe Reader in the dialogue window that opens and also place a check mark in the "Always use the selected program to opent this kind of file" box, and then select the OK button. Vista should be similar, but I don't remember for sure how it is done (don't like Vista-I use XP at work).