This morning I had the problem that when I opened visual studio 2005 it started complaining about the fact that a workspace was already mapped to a specific path. Visual Studio somehow forgot that I had indeed mapped the TFS project to path on my harddrive and I had to manually fix the problem.
To fix this issue I modified Sourcecontrol.config in C:Documents and Settings<Username>Local SettingsApplication DataMicrosoftTeam Foundation1.0Cache and removed all ServerInfo elements from the file. You get rid of the mappings that were created by TFS, but keep the files.
After removing the elements save the file and start visual studio again. Now you can remap the workspace and continue the files in your local workspace.