[link|http://www.theregister.co.uk/content/55/30199.html|Register].
The more serious problem, involving Microsoft's virtual machine (Microsoft VM), which enables Java programs to run on Microsoft Windows, provides a mechanism for attackers to run amok on Windows PCs. Microsoft has released a fix designed to address the problem, which affects users of Windows 98, NT 4, Windows 2000, XP and Windows Me.
If you got one, get the fix and promise not to rat on .NET performance problems.