Error saving Project 2010 files to network drive - doesn't see network drive

Question

ANSWERED (11 April 2014):
So it seems the resolution to this is to simply create a new share with a different name. I used the existing folder (to retain NTFS permissions) and just select to Add a new Share (applying the same Share permissions as the non working Shares).
Deploying this new Share via Group Policy as a test resulted in staff being able to open files from Windows Search, save files through MS Project and the Share being accessible through browsing SMB.
All problems resolved by using a new share name for the existing folder. Seems to be a corruption in the namespace.
Note: I had previously deleted the share and recreated it. I had removed all NTFS permissions and readded (through both the GUI and icacls). This didn't make a difference.
Only changing the name of the share fixed the problem.
Original Question
Already
posted here... but Microsoft Support has not responded.
It seems some staff on some computers are having problems saving MS Project files to the network. This is only since an upgrade to SBS2011 (from SBS2003). The only difference now, is that network drives are mapped via group policy rather than a  'net
use' script.
This is affecting users on Windows 7 and Windows Server 2008 R2, with either MS Project 2007 or 2010. The users have full change access to the folders and can create new files and modifying existing files, just not a MS Project file. Other file tyes, e.g
Word .docx, Excel .xlsx, Adobe .pdf files, all work fine. These files can be opened, edited and saved normally without problem.
To replicate this:
The user opens an existing file or creates a new file on the network folder (either through Windows Explorer or MS Project). They then click File > Save in MS Project and receive the following error (see pic below):
An interesting symptom of this is that if you select File > Save As in MS Project, the Sae As dialog box doesn't remeber the path location of the network drive. MS Project instead prompts to save the file in the local users documents folder (see pic below):
If they browse back to the original folder where the file was saved and choose to save it there, they are of course, prompted to overwrite the existing file and they can save the file. But the same thing happens every time they open the file.
It seems the problem is that Project isn't seeing the path of the file or that the network drive is attached.
If a user closes the file without saving it, they are prompted to save the file and the prompt shows the drive path:
   Do you want to save changes to "N:\... Projects\Active Projects\CC...\F4 Project Plan File\004 Programme\test project file.mpp"?   
But choosing to save the file gives them the same result as Save As, they are prompted for a new location as if the original file location doesn't exist.
I have disconnected the mapped drive and connected it again using net use but get the same error.
I have reinstalled MS Project 201, installed Project 2010 SP2 and installed Windows updates and it does the same thing, exactly the same symptoms.
Further, if the user opens a file from the network drive, the file shows in the Project recent files list. If they try to open the file from the recent files list in project they get the following error:
"Project cannot open the file.
-Check that the file name and path are correct.
-Check that the file format is recognized by Project.
Project files saved in a version earlier than Microsoft Project 98 can't be opened...."
This is a test file that I created on the user's computer and network drive, This is being opened with the same version it was created in. If I browse to the folder in Windows Explorer I can open the file. Of course, I then can't save the file (I still get
the original error). I'm logged on with Domain Admin privileges.
I've checked these links from other threads (neither apply to my scenario):
http://support.microsoft.com/kb/983458/en-us|
http://social.technet.microsoft.com/Forums/en-US/excel/thread/2eeea140-7e6c-4cb9-a89b-06d2102bd9f7/
I've downloaded my TechNet version of he software and installed it with Sp2 and Windows updates and it does the same thing. This also happens on the Remote Desktop server (Server 2008 R2) using MS Project 2007.

Answer 1

Case 1
This error message appears when the document is open on two or more computers that are running different operating platforms. For example,
if the document is open on a Macintosh computer and you open it on a second computer running Windows or Windows NT, the error occurs when either user tries to save the document.
This problem stems from a difference between the ways Macintosh OLE and Windows OLE open files. As a result, you cannot save a file on two different operating platforms at the same time.
Case 2
This error occurs in Word 97 for Windows if you save to a MAPROOT type network drive connection on a NetWare server where spaces exist in
the file or folder name.
Case 3
This problem may occur if an anti-virus program running on a network has the ability to scan for macro viruses in documents in shared network
folders.
For example, if you have the following:
a shared folder on a network server
-and-
an anti-virus program is running on the network server that is set to monitor the shared folder,
when you attempt to save a document (across the network) to the shared folder, the anti-virus checker may cause the error to occur.
Case 4
This problem may occur on Novell networks when the AutoRecover files path is either blank or set to a network drive.
According each, please try the following workaround:
WORKAROUND
To work around this problem, use one of the following methods appropriate to your situation.
Case 1
Method 1:
Move the document to your local hard disk for editing. Move it back to the server after you finish.
Method 2:
Save a copy of the
file with a different
file name, and work on the copy, either on your hard disk or on the server.
Case 3
Method 1:
Move the document to your local hard disk for editing. Move it back to the server after you finish.
Method 2:
Do not use spaces in the directory or document names.
Method 3:
Do not use MAPROOT-drive connections. Map your drive connections to the volume-level only.
Case 4
Turn off the anti-virus protection on the network server and then try to
save the document. Contact your anti-virus protection software company for additional details and/or updates to their programs.
Case 5
Set the AutoRecover files path to your local drive. To change the AutoRecover path, use the following steps:
1.
On the Tools menu, click Options.
2.
On the File Locations tab, select AutoRecover files and then click Modify.
3.
Change the Modify Location dialog box to a
folder on your local drive and then click OK.
4.
Click OK to close the Options dialog box.
Hope that helps.
Smith