Update:
Got a new cable modem from the ISP, and it appears to be working fine. Looks like this issue may be solved.
but I'm not calling it solved until a good week's worth of using it.
HOWEVER
After the modem switch, the elderly computer will log on via wireless for roughly one minute, then disconnect. Reconnecting (manual or auto) only occurs after restarting the computer.
Haven't tried hardwiring the old computer to the modem yet due to the sleeping child the modem's room. Was able to check local, mask and router ISP's on both computers and they look correct with the new modem.
CommoNCO: We're on a secure wireless router. Neighbors are reliable; street is deserted.
Maytime: Cable modem. Thanks for tracrt command and DNS info; that should come in handy. Hoping not to use it
ISP will be contacted tomorrow, and I'll post more questions or the solution tomorrow
Thanks,
Rumbly