Error while saving a .PDF File to a mapped drive

The issue I am having is similar to the one found on this older post. http://forums.adobe.com/message/3066663#3066663

The issue is as follows. I have a small company about 15 users divided into a couple of departments with different networking access needs. They each have Adobe Acrobat version XI installed on a Windows 7 Platform. Each user has a set of mapped drives that correspond to their department. The Disk mappings are all directed to the main shared Network Attached Storage (NAS) device. At any time there can be a number of PDF files open and being worked in. The same PDF is usually not opened at the same time from two different locations.

The issue is that two users who do a large amount of the work, IE. Scanning documents and adding them to documents that have been previously created, are reporting the same issue. The issue is when they have the PDF document opened and they are adding new content. Once the new content is added they go to save the document and then receive the following error:

“The document could not be saved. Cannot save to this filename. Please save the document with a different name or in a different folder.”

In order to save the file the user has to use the save as function and then browse to the original file location to save the document with the changes that have been made.

Along with the above error we have noticed that Adobe Acrobat is renaming the file that has been changed to aae##### or aak##### or aan#####. The file name is changed causing the normal save function to not work correctly.

Is there a reason Acrobat would be doing this?

I am not using Microsoft SharePoint.