It was possible to freeze or reboot Windows by reading a MS/DOS device through FTP, using a file name like CON\CON, AUX.htm or AUX. A cracker may use this flaw to make your system crash continuously, preventing you from working properly.

upgrade your system or use a FTP server that filters those names out. Reference : http://support.microsoft.com/default.aspx?scid=KB en-us Q256015 Reference : http://online.securityfocus.com/archive/1/195054