I've received this message in the eventviewer on my exchange server. I don't think it's an exchange related problem but hopefully you know what the problem is. I search this forum first but I only found people who had this same problem on workstations only not servers.
L. van der Meer
Windows saved user KNB\Administrator registry while an application or service was still using the registry during log off. The memory used by the user's registry has not been freed. The registry will be unloaded when it is no longer in use.
This is often caused by services running as a user account, try configuring the services to run in either the LocalService or NetworkService account.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp