“Failed to load the workflow” Message in SharePoint Designer

I’m working at a new client and just getting the machine that they have me using working the way I like it.  I tried to open a workflow in SharePoint Designer and got the popup dialog: “Failed to load the workflow.”  (I had already loaded .NET 3.0 to get the Workflow Foundation Classes.)
A little searching, and I found the answer in Scott Muller’s blog: Navigate to C:\Documents and Settings\<your user name>\Application Data\Microsoft\SharePoint Designer\ProxyAssemblyCache and delete the existing folder (12.x.x.xxxx).  (You’ll have to shut down SharePoint Designer for the delete to work.)  I’m not sure why it works, but it works!


Have a thought or opinion?