This indicates an attack attempt against a code execution vulnerability in Microsoft Windows.
The vulnerability is caused by an error when the vulnerable software is parsing a malicious HTML Help File. It may allow remote attackers to execute arbitrary code by tricking a user to open a crafted ".chm" file.
Windows XP SP3 fully patched
Windows 2000 SP4
System Compromise: Remote attackers can gain control of vulnerable systems.
Currently we are not aware of any vendor supplied patch for this issue.