Here you go so it doesnt happen in the future:
Add this to your boot.ini file, and no more serial mice.
/NOSERIALMICE=[COMx | COMx,y,z...]
Obsolete Windows NT 4 qualifier-replaced by the absence of the /FASTDETECT switch. Disables serial mouse detection of the specified COM ports. This switch was used if you had a device other than a mouse attached to a serial port during the startup sequence. Using /NOSERIALMICE without specifying a COM port disables serial mouse detection on all COM ports. See Microsoft Knowledge Base article Q131976 for more information.