TFS30421 Error when trying to connect from Team Explorer

Source: Microsoft Support

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You attempt to connect to Team Foundation Server 2005 or 2008 from Team Explorer.

The following error appears:

TF30421: Team Explorer could not connect to Team Foundation server <servername>. The server may be offline
or the network is unavailable. Contact your Team Foundation Server Administrator to confirm that the server is available on the network.
Use the connect to Team Foundation Server Command on the Tools menu to retry your connection to the server.

The server returned the following error:Unable to cast COM object of type 'System.__ComObject' to interface type 'Microsoft.VisualStudio.OLE.Interop.IServiceProvider'. This operation failed
because the QueryInterface call on the COM component for the interface with IID
'{6D5140C1-7436-11CE-8034-00AA006009FA}' failed due to the following error: No such
interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).

Try manually registering the following files:

Urlmon.dll
Mshtml.dll
Actxprxy.dll
Oleaut32.dll
Shell32.dll
Shdocvw.dll

For example, click on Start, and then choose Run, and in the Run dialog type:

regsvr32 Urlmon.dll

You don't have to specify the path when registering the files, but these files are located in the %windir%\system32 folder.

If registering the files does not fix the problem, run a repair on Team Explorer/Visual Studio using the Add/Remove programs in Control Panel or Programs and Features (in Vista and Windows 2008 Server).

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