Hello Vogons,
A friend of mine owns a Chaintech 5AGM2-H150 motherboard. It have problems with the serial ports, they are enabled in BIOS but when he attaches a serial mouse to either COM2 or COM1 it does not work. I mention that the mouse works on another PC and also the serial ports are enabled in BIOS. Maybe the serial ports are screwed or it is something related with board? Any help please?

Also it can be a IRQ conflict because he also have a 56k ISA modem put as COM3 and with IRQ 4 (also the COM1 port have IRQ4 and the COM2 port have IRQ3)? Also he tried with the modem removed and it is same. EIther with modem or without modem, COM ports cannot work. What it can be?