TF10121: The path '' is not found or not supported. Type or select a different path. After SQL2012 install and Solution upgraded to VS2010

I have recently upgraded a solution from vs2008 to vs2010.  This solution happens to contain several .rptproj file (SSRS 2008R2 reports).  I was able to upgrade the solution after I installed SQL2012 (which installed the necessary templates into vs2010). 

However whenever I open the solution the Output window now pops up and continuously lists the same error (shows output from Source Control - Team Foundation).

TF10121: The path '' is not found or not supported. Type or select a different path.

I have tried reinstalling Team Explorer SP1, and VS2010 SP1, but with no change.

If I unbind the solution from source control the messages go away.  Rebind and they return.

The problem doesn't always start straight away, it may take a few solution explorer clicks.

Opening an rdl into the editor seems to halt the messages, until I go back to clicking in solution explorer (similarly the issue doesn't always re-occur first click).

E.g.

TF10121: The path '' is not found or not supported. Type or select a different path.

...

TF10121: The path '' is not found or not supported. Type or select a different path.

Audit.rdl has been automatically checked out for editing.

Then no errors until going back and clicking in solution explorer (which is using auto hide)

[See also: http://social.msdn.microsoft.com/Forums/en-US/tfsversioncontrol/thread/8c7cc472-3ac1-4800-8199-5f4b41414748]

Does anyone else out there share this problem or more importantly a solution/work around?