SPI Labs labs reports a vulnerability in Microsoft's IIS. "If an attacker sends a Webdav request with a body over 49,153 bytes using the 'PROPFIND' or 'SEARCH' request methods, IIS will be forced to restart itself. All web server, email, and active ftp connections will be terminated, along with a disruption of future sessions during the time it takes IIS to restart," its advisory states
For a patch and more information go to http://www.microsoft.com/technet/security/bulletin/MS03-018.asp