Serial port problem with W2k

Good day to you all. Sorry, if, as a new member, I'm doing this all wrong. But anyway, I have a problem that puzzles me.

I have an old Asus Mel-M motherboard using Intel's 440LX-chipset. For some reason, Windows 2000 and motherboard's serial ports can't cope with each other. Device manager shows a yellow exclamation mark over the two ports, and says they are not functioning correctly, and that I should contact the vendor. No IRQ conflicts are present, anyway not any that W2k informs of.

I have changed the IRQs of the ports, and I have disabled one of them. I have tried to update W2k's chipset drivers, but the setup program says W2k already supports my 440LX.

Odd thing is, with Windows 98 these ports work as they should.

Thank you for any possible help.