Internet Restarting Computer

[kkjensen]

A co-worker of mine is having issues with his Win98se based computer. The computer works perfectly under normal operation. He is connected to a cable modem via a NIC card. When he launches Internet Explorer the entire computer will re-start incorrectly requiring scandisc to run before loading windows. Obviously something is terribly wrong. So far I have had him do a thorough Scandisc and Defrag. I had him attempt to do a windows update and as soon as it analyzed his computer it rebooted (incorrectly again). It is almost like you just hit the reset button. I have built computers for years and never heard of anything like this. He has a younger son who says he has done nothing out of the ordinary to the computer. He is using Norton Antivirus 2002 and Norton Personal Firewall, all virus definitions are up to date and a complete system scan says everything is fine??? I'm lost!! Is there some posibility that his network configuration could cause this? I don't believe it is Internet explorer related since Windows Update doesn't use it. The longest he has been able to stay on-line is 5 minutes before the automatic system restart? Please give me any advice to try.
Thanks,
Kevin
System:
Hewlett Packard PIII 800
128mbram
40gig drive
(That is all I know about it as of now, I'm trying to help him via phone and notes at work)

[Cricket]

Hi kkjensen,

What NIC is installed in that HP? Did the problem start right after the cable internet connection was installed?

Has he checked to see if the NIC is sharing a IRQ with anything?

Was any other hardware installed on the system recently (CD-RW, another hard drive, etc...)?

Cricket

[kkjensen]

Unsure which NIC he is using...haven't looked at it yet. He had the cable modem installed about 3 weeks ago and it had been working flawlessly and just started re-starting for no apparent reason. I haven't had the opportunity to go over to his house yet..I just wanted some ideas before hand.