Apparently regmon now crashes Windows Server 2003 systems that are patched with the latest Microsoft updates. I left regmon running unattended for about 30 minutes and the system suddenly stopped responding to all network connections with the error:
"Not enough server storage is available to process this command."

The System event log was filled with messages like this:
"Event Type: Error
Event Source: Application Popup
Event Category: None
Event ID: 333
Date: 10/31/2007
Time: 5:04:45 PM
User: N/A
Computer: DRSERV1
Description:
An I/O operation initiated by the Registry failed unrecoverably. The Registry could not read in, or write out, or flush, one of the files that contain the system's image of the Registry."

I was unable to login, even from the physical console. Some research showed that this has been happening to others as well.