Preview not opening email attachments…

Nothing I receive via email opens in Preview…. I try to save then open, but this doesn't help either.
The error message reads:
"It may be damaged or use a file format that Preview doesn’t recognize."
.pdf in emails won't work, but ones already on my mac are fine… ??
Running 10.7.5 and Entourage email (Office 08) and GMail.

Surely it's a preference setting somewhere right?

Please help…

Try this. Quit all mail programs, then open Finder. In the menubar goto Finder>Go and click on the ⌥ Option ket and you will see Library pop up (this is hidden by default) Click on Library>Mail>V2 and look for the OpenedAttachmentsV2.plist Drag this to your Desktop. Open Mail and try opening a attachment. Mail will automatically make a new OpenedAttachmentsV2.plist so if this works, drop the one on your Desktop into your Trash.
If it doesn't work, put it back and click Replace. Then try Repairing Permissions via Disk Utility next and once done restart again and try again.
If those fail, drop back and let us know.

Cheers