Could be an IRQ conflict between the video adpater and the network card.
Check msinfo32. See 184075 Description of Microsoft System Information
(Msinfo32.exe) Tool
http://support.microsoft.com/?id=184075
--
Thanks,
Marc Reynolds
Microsoft Technical Support
This posting is provided "AS IS" with no warranties, and confers no rights.
"niall" <(E-Mail Removed)> wrote in message
news:028f01c3d8c3$43364bc0$(E-Mail Removed)...
> When Cable Modem Network Cable is plugged into Windows 98
> machine, the moniter goes Black less than a minute after
> the PC starts up.
>
> When not plugged into cable modem, the PC and moniter
> work just fine!
>
> Any suggestions?
>
> Thanks
>
>