After running for an extended period, my father's computer stopped
connecting to the internet. The modem doesn't respond.

It reinstalls on comm port 3 and the computer only acknowledges comm
ports 1 and 2. I removed it from there and reinstalled in on comm
port one but it doesn't respond there. The message in control
panel/modems/properties/diagnostics says to verify the interrupt for
the port is properly set. The interrupt is 4.

Everything in cp/system displays OK with no conflicts. It says the
modem is working properly. I downloaded a driver and burned it to a CD
but the computer wouldn't accept it.

The computer uses win98SE. The processor speed is 350.

Any ideas what went wrong and how to fix it?

Best,
dd