Sometimes you will login to TOAD on a DB that has been configured to use VSS, and receive the error message: "A required resource file could not be found on your computer. To resolve this issue, run setup to repair your Visual SourceSafe Installation." Now, you can run a repair install, and all will be well once it is done, but there is an easier way.
A quicker fix is to go find the ssapi.dll and re-register it.
C:\Program Files\Microsoft Visual SourceSafe>regsvr32 ssapi.dll
Go back into TOAD, and you should no longer receive the warning message.