Messenger Service

From: William C. (cmchong20_at_yahoo.com)
Date: 11/27/03 

Date: Thu, 27 Nov 2003 16:05:09 +0800

Some of my Win2k server & WinNT server sometime pop-up with a "Messenger
Service" with the detail,

"Message from EvidenceX.com to ........ on 15/11/03 11:24PM.
  You are being watched... how about your Boss? Do you surf the internet and
email at work? Your work PC will be full of evidence. Destroy your evidence
and save you and your family! Go to EvidenceX.com and get free download."

What is it all about? Is the machine being hacked?