PS/2 mice suddenly stopped working

[Greg Mars]

I just turned on today and my ps/2 mouse (actually SB with a ps/2 adapter)
was not working.
Tried reconfiguring in sysinstall to no avail.
Tried another pure ps/2 mouse and it didn't work either.
Took off the usb-ps/2 adapter off the original mouse, plugged it in a usb
port, and now it works.

Everything used to work just the day before.
I guess it's possible something could be wrong with the  port
(which would be sad since the motherboard is probably 2-3 weeks old)

Does anyone have any ideas on how to test this?
I don't have another OS on this box and installing one won't be easy.