Acrobat X - Can't save after edits File may be read-only or another user may have it open

2 users out of about 150 aren't able to save files unless they rename them or save elsewhere. The error message they get is "The document could not be saved. The file may be read-only, or another user may have it open. Please save the document with a different name or in a different folder."

If  the user closes the original folder before saving it will save with 1 click as normal.  Also turning off preview in explorer will resolve the save glitch temporary but it comes back after a few hours. I did read on a few other forums that turning off enhanced security resolved the problem, however for it hasn't made a difference for me here.

Any ideas?