This indicates a possible attempt to exploit a Buffer Overflow vulnerability in Microsoft Internet Explorer.
The vulnerability is caused by insufficient boundary checks by the application, and can result in arbitrary code execution or a Denial of Service condition.
Microsoft Internet Explorer 6.0 SP1
Microsoft Internet Explorer 6.0
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the appropriate patch for your system, as listed in Microsoft Security Bulletin MS06-042.