This problem is typically caused when a Visual InterDev project is under source control and the Visual SourceSafe database is unavailable because it has been moved or uninstalled or there are problems with the VSS configuration.
The FrontPage Server Extensions save metadata information regarding the checked in/out state of a file. In this scenario, they are unable to contact the Visual SourceSafe database and therefore raise the error.
To verify this, you can easily check the metadata for several files. This information is stored in the _VTI_CNF folder beneath each folder on the Web server. Entries that indicate the files are under source control are:
vti_sourcecontrolcheckedoutby:SX|REDMOND\\scottsta
vti_sourcecontrolmultiuserchkoutby:VX|REDMOND\\\\scottsta
vti_sourcecontroltimecheckedout:TX|15 Apr 1999 12:52:03 -0000
vti_sourcecontrolcookie:SX|D:\\Program Files\\Microsoft Visual Studio\\Common\\VSS\\srcsafe.ini
vti_sourcecontrolversion:SX|V1