This has nothing to do with microsoft's COM dev. system, its just an old dos device name. There are various reserved words in DOS, com3 - (ie, communication port 3) is just one, com1, com2, wont work either. Nor will PRN (printer), LPT1 (parrallel port 1) LPT2, LPT3, CON, AUX, or COM4.

Our little friend here has either had a joke played on him, or is playing one.