We are sharing a PowerPoint 2010 presentation between two users via email. User 1 can open the file, save it on her Desktop (Win7), modify it, no problem.

User 2 can open the file, but it is Read Only. She cannot File | Save As and save it, there is nothing in the Options area turned on different from User 1, the file itself is not Read Only. We have restarted her machine. I had her open another PowerPoint file and save it and that worked fine. I had her copy the file into a new file, still does not save. I am mystified. Any ideas would be greatly appreciated.