We came up with the issue that there are one of the following errors regarding the TFS 2008.

Either you are unable to bind a solution at all, showing:

The solution you have opened is under source control but not currently configured for integrated source control in Visual Studio. …

Or the solution is opened without source control, showing:

The solutions appears to be under source control but its binding information cannot be found. …

Output Window: The solution is offline because its associated Team Foundation Server is offline.

The solution is quite simple: Recreate the server entry in Visual Studio 2008:

1) Close the solution

2) Disconnect the TFS

3) Remove the server

4) Re-add the server

5) Open the solution. Everything should be fine now.

Q: http://markitup.com/Posts/Post.aspx?postId=6355ea6f-3af6-4cfc-86b0-b6467de2cd0d
Q: http://social.msdn.microsoft.com/Forums/en-US/tfsversioncontrol/thread/308255ac-2e10-426c-996c-ca62321c8e1f