Event Log Error 7005

Almost every night shortly after midnight, we get the following error on almost all servers:

Error Number: 7005

Text: The RplImpersonateClient call failed with the following error:
No security context is available to allow impersonation.

Background: All servers have a command file scheduled to run at midnight to stop and start the Performance Data Log service(installed from Resource Kit) and store data on a different server.

Can anyone tell me what the error means and how to go about correcting it?