Whist moving Team Project Collections (TPC) from our old TFS2010 Beta/RC server to new production hardware I got a TF261007, exactly as detailed in Marcel de Vries post. However, I was in the better position than he was as I still had full access to my original server, so I thought I could go back, re-attached the TPC on the old server, run the command
tfsconfig lab /delete /collectionName:MyCollection /External
re-detach and all would be OK.
This was not the case, you still get the same problem as TF261007. It seems that if you have a TPC what has ever been on a TFS 2010 RC server with Lab Management configured then it can only be moved to a new server that also has Lab management configured, or at least SCOM VMM console installed and pointed at VMM Host.
I checked this with Microsoft and was told it is a known issue with the Lab Management RC and will be fixed in the RTM, for now there is no other workaround other than the one Marcel detailed.