System Event Notification Service

After installing the latest batch of updates, restarting, and logging into my
user account I received this error: Windows could not connect to the System
Event Notification Service service. Please consult your system administrator.
I clicked the OK button and was automatically logged off and presented with
the log in screen. I logged into my user account with no other problems and
have not tried restarting again.
Any ideas as to what might have caused this problem? It is the first time I
have seen it.
Thanks in advance for any info.