losing browser, but not outlook express

Windows 2k pro SP4
IE 6
no firewall, McAfee virus software
connecting through 3com adapter to
switch 100 BT cat5:
two other clients, Win98 & Xp no problem
with Verizon DSL link out of switch.
station in question will load mail, browse
for three to five minutes then timeout.
Outlook Express still works.
Need to warm start for browser to come back.