I think you may want to open a Support case as there are a few things that may be causing this issue. It's possible there's a permissions issue preventing Tableau Desktop from opening that filepath. You can try testing this by opening Tableau Desktop as an administrator and seeing if the workbook loads.
Another possibility is that the workbook has been corrupted. If that's the case, you'll want to work with Support to see if the workbook can be salvaged. I recommend including the below information if you choose to open a support case:
1. What version of Tableau Desktop are you using now?
2. Is it possible to unzip the packaged workbook and open the .twb version of the workbook?
3. A copy of the packaged workbook.
4. Please send along a set of Clean Tableau Desktop Logs.
a. Make sure all instances of Tableau Desktop are closed.
b. Navigate to My Documents > My Tableau Repository
c. Rename the "Logs" folder to Logs_Backup
d. Recreate the issue, then close Tableau Desktop
e. Send Tableau Desktop logs. Please see http://www.tableausoftware.com/support/knowledge-base/sending-tableau-desktop-log-files for instructions on bundling and sending the files.
Hope this helps!
Looks like its corrupted. Can you get the xml version of the .twbx and share it with the support?