Test Studio attempts to check out a test from TFS every time Test Studio opens, even when that test has not been recently checked in to TFS.
An error like this appears in the application log:
[02/04 14:33:22,Telerik.TestStudio.exe(2920:1),TeamFoundationServer] TFSServer._vcs_NonFatalError() : Non-fatal error handling TFS request: Failure instance 52192065 RequestType: None Code: ItemExistsException Severity: Error Warnings:  ComputerName: IdentityName: LocalItem: Message: The item $/TestName.tstest already exists. [ . . .] [02/04 14:33:22,Telerik.TestStudio.exe(2920:1),TeamFoundationServer] TFSServer.AddFiles() : Error adding files
This behavior may occur if you attempt to open a project on your local hard drive that was connected to a different TFS workspace.
Instead of copying the project from another machine, try opening it from TFS. This way, Test Studio can properly setup the TFS workspace on your local machine.