Vista - System Event Notification Service Failure

This problem just started happening on Wednesday, November 14, 2007.

I logged on to the computer as an administrator, and a Windows notification
tells me that "Windows could not connect to the System Event Notification
Service service. This problem prevents limited users from logging on to the
system. As an administrative user, you can review the System Event Log for
details about why the service didn't respond."

I have searched the discussion groups and have found no solution to this
problem as of yet. As an interim measure, I have switched all user accounts
to use Administrative privileges until such time as the problem can be fixed.
Meanwhile, can anyone out there give me any help with this error?

Brandon Taylor