P/I-P55T2P4: Mouse not working on PS/2 or serial port

Hi All

I have an old PC with an Asus P/I-P55T2P4 motherboard, I have Windows
98 SE installed. This PC was working well, but one day the PS/2 mouse
was not working anymore. The BIOS is version 2.07, the latest I found.

I did the following tests on this computer:

I checked the voltages on the power supply - motherboard connector,
they are fine.

I booted with a DOS disk and loaded the mouse driver, but it didn't
find the mouse.

I plugged a new mouse from another PC, but it was also not working.

I removed the PS/2 mouse and tested a serial mouse on COM1, then on
COM2, in both cases the mouse was not working.

I thought maybe there is a problem with the I/O controller chip and I
installed a serial port card, disabled the on-board serial ports, then
tested the serial mouse on this serial port, the mouse was not
working.

I repeated the test with the PS/2 optical mouse from my newest PC,
there I noticed that the LED never goes on. On my new PC, the LED is
on as soon as I switch on the PC.


Can someone explain me what could be wrong with this PC? What can I do
with this PC to have the mouse working again?
I know, it's an old PC, but it's fast enough for what I use(d) it.



Thanks in advance for your help

Michel