Unable to save pdf form

I have a user that is no longer able to re-save/overwrite pdf forms.

Facts:

1. He is using Reader XI.
2. The files are located on our server in a shared folder.
3. He is able to save his changes to any other programs files in the folder just fine.
4. Others can save their changes/signatures to the same pdf forms just fine.
5. When he first created his signature he was able to save his changes for a couple of weeks.
6. The issue is only on his PC - when he logs in on another PC, he is able to save.
7. The message he gets states that it may be a read only file or that it is being used by someone else - but it is not, and he only gets that when it is opened from his PC.
8. I tried removing the signature within Reader.
9. I tried uninstalling all of his Adobe programs (i.e. Flash, Reader, Air, Shockwave).

Any suggestions? Thank you in advance for your help!!!