Machine reboots when connected to the internet

To be precise - it reboots when a broadband modem is connected via USB. It doesn't reboot if the same modem is connected via a NIC.

It used to reboot between 5 and 60 minutes at random. So I thought it must be an IRQ conflict. I looked at the device manager and found the NVidia Geforce2 was on the same interupt, and was running MS drivers. So I downloaded the latest NVidia drivers and installed them. Now it reboots as soon as it goes into Win XP if the modem is connected to the USB port, and runs like a dream if it isn't.

This I think proves its an IRQ problem. However as the graphics card is AGP I can't move it to another slot. I cannot disable it as theres no other video. I cannot disable the USB ports because they are needed. And when I go into the bios to try and manually assign the graphics card and AGP to different IRQ's, I find they are all bundled together and I can only change both USB and the video to another interupt, not separate each.

The machine is a clients - an ADVENT desktop, and the original drivers aren't with it. However I have downloaded the mobo ones from MSI's site, and apart from the graphics card all others are MS and showing no conflicts.

Any help would be appreciated.

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NetExpertConnect With a Mentor Commented:
1. Remove the graphic card, with the modem plug to USB and start the PC. Does it reboot?
2. Put everything together, start the computer and let it reboot. Then remove the modem and start the PC. Look at the event log to see if any service goes wrong.
3. Check the USB connector of the modem (which model is that by the way?). Test the USB modem with another PC. USB failure may reboot the PC.
4. Remove the USB and start the PC. After everything loaded, plug the modem on USB port (Plug and play should be working, it will be risky somehow, but at least you will see how far the OS detect the modem before it fail).
5. Remove everything else plugged in the USB port. One of the reason it fails is that USB may not support enough power to all external devices.
6. Set IRQ for the graphic card manually (using resource tab), then plug the modem on.

Just toggle around, and you may find the problem. Good luck.
krakersAuthor Commented:
1 and 2 will have to wit until I'm back at the clients.

3 USB connector is fine - have swapped out cable and behaves the same with any. The modem is a Motorola surfboard - stadard Blue Yonder kit. The Modem works fine on other machines.

4 Again I'll do this when back on site, but given where it currently reboots its within seconds of the drivers being loaded.

5 Already done this with no success. You should note the modem is passive, not drawing any power from the USB port.

6 I'd love to change the IRQ only I can't. Its greyed out - I think you can only alter it if Windows detects a conflict, which it currently doesn't. As stated previously the AGP and USB ports are tied into the same resource in the Bios, and no seperating them there.

HaraiSuruConnect With a Mentor Commented:
Just a note... I have found that some systems just do not like the USB interent connection at all... I have seen them reboot and even freeze for several minutes at a time when trying to access the internet.

You Did say though that is works like a dream through the NIC. Is there some reason that you do are not wanting to use it via ethernet...?

I have found ethernet to be prefered over USB anyday reguardless.
krakersAuthor Commented:
Its a clients machine, not mine, and I originally set it up for them via ethernet. I was called back when it started to reboot only to discover they'd moved it over to USB. The reason for this is they wanted to enable ICS with a number of other machines using Ethernet conections. Its their choice and my job to make it work - although its proving tricky so far.

krakersAuthor Commented:
The client never came back to me to arrange another time to progress, so unfortunately I don't have a resolution to this problem. I am fairly sure it was some kind of USB conflict, so splitting the points between experts for contributing plausable tests.

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