Spontaneous reboot at network connection

[Guest]

Hello,
I've got this nasty problem with one computer in a network that will
reboot as soon as an attempt is made to open a map or file. It will
give a little plop, go black and reboot.
Strange thing is that I have full access to that computer when I don't
start up Windows entirely, that means that I leave it where Win98
gives the popup window to confirm the network password.
Although I posted this in a hardware group it might be a software
problem after all, I just don't know.

Oh, and the same reboot will happen when an internet connection is
made by telephone modem. As soon as the connection should be there it
goes black and reboots.

Does anyone have an idea what is this and what to do about it?
I'd be so much obliged.

Regards

 

[BruceM]

For starters boot into safe mode & turn off "reboot on all errors".

 

[BruceM]

Oh, oooops..... sorry I just noticed it is 98.

 

[Guest]

In case this might be useful to others: it appeared to be caused by
the video card, a SiS 6326 card.
Beats me why, but now I've switched it off everything works fine.
Except my video of course.