The company I am employed by has been running SharePoint 2010 successfully for several months now. Recently when anyone attempts to connect to our main site using SharePoint designer they are prevented from doing so an given the following error message: "Server Error: The version of Microsoft SharePoint Foundation running on the server is more recent than the version of SharePoint Designer you are using. You need a more recent version of SharePoint Designer". We are running the most recent version that we can find available for download from Microsoft. The server administrator has attempted to roll back the most recent patches / updates to SP Foundation, rebooted the site collection, tried a fresh install of Designer and other obvious common solutions to no avail.
This is the build of SPDesigner we're running: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=d88a1505-849b-4587-b854-a7054ee28d66&displaylang=en
How do we resolve this problem?