I have a user that uses Excel a bunch. He recieves reports and assignment sheets from other users as well. Right now, if he tries to double click on a file in an email, it will open excel but not the file. Make sense? Same goes for a shortcut to a file. It'll open excel, but not the file. However, you can still open the file from "File > Open" option in the menu. I've uninstalled/reinstalled, ran spyware/virus checks, rebooted, poked and tinkered and I cant figure it out. Have you guys heard of this one?
Sounds like a file association error... make sure the user is a local admin on the PC, then right click file, use open with, and choose the check box that says always open this type of file with this program. This should solve the issue... that being said you can then set them back to their previous level of authorization. Hope that helps. Sak.