Network freezing up computer? Anyone know why?

Maybe one of you may be able to shed some light on this issue.

Have a Gateway 400mhz Pentium ][, 128 mb ram. It was acting up,
crashing the network it was in so I wiped the HD and reinstalled Win
98 and all drivers. Ran like a champ till I went to access the
network, then it would freeze up and not come back. Installed a new
Network card and drivers, did the same.

Put in a new HD, changed the memory chips, new clean install of win
98, did the same a again with both network cards.

It would connect to the network , get a partial web page or drive
listing then seize up. If I didn't access the network the machine runs
for hours with no problems? Any idea what could cause this? could
there be a problem with the bus / irqs?

Any thoughts would be very helpful. This machine has been running
Windows 98 since 1999 with never an issue, now this.

Have another machine exacly like it with 256mb running xp for over a
year with no issue like this.


Bill H