My PC sporadically loses Internet connectivity. The failure mode happens
more and more often. Now it's few times a day. I'm concerned about losing
connectivity entirely.

The failure can happen during periods of Internet activity or of
inactivity. Most often, it happens on a reboot.

Can somebody help me get rid of the problem?

Configuration:
Windows 98
Cable Internet using SurfBord SB3100
SMC USB Ethernet Adapter 2202
MSIE 6.0 (problem also happened with earlier versions)
Mozilla 1.0
ZoneAlarm 3.7 (problem also happened with earlier versions)
AVG 7.0 (problem also happened with McAfee)
Intel AnyPoint to connect with an older PC


The symptoms are different with different applications.

* MSIE usually asks me to choose a connection to dial, even though I've set
Internet Options Connections
to "Never dial a connection." Somehow, something overrides this
setting. (Other times, MSIE times out during DNS lookup.)

* Mozilla just times out.

* Outlook reports "can't connect."

* AIM reverts to not-signed-on mode.


In failure mode:

* No application can access Internet, but local activities are normal.

* The PC cannot connect to the modem using 192.168.100.1 in the browser
address bar (apparently ruling out an outage of DNS service). Likewise,
can't ping 192.168.100.1.

* The PC can intercommunicate with the older PC for file/printer sharing.
(Most of the time, the older PC is powered off. Whether it's on or off
seems to have no bearing on the problem.)

* The older PC cannot access the Internet (it connects to Internet
through this troubled PC). AnyPoint reports "can't find Internet server."

* IPconfig shows several days left on the IP address lease. It also shows
that
the most recent lease renewal preceded some successful Internet activity
(apparently ruling out a DHCP-related problem).

* The cable modem's lights appear as usual.

* The NIC's Link/Act light flashes as usual.

* Rebooting typically restores connectivity, but sometimes a second
reboot is needed. Occasionally, it's enough to just re-assert
"Never dial a connection," close applications, retry, and get MSIE
out of "working offline" mode.

* Afterward, the cable modem's log shows no events for several days
(apparently ruling out an ISP outage or a cable-modem failure).

I can't help thinking that different software components are tripping over
each other in such a way that Internet access is blocked. Since the problem
often happens on a re-boot, maybe the start-up programs by themselves are
to blame. For reference, my startup folder contains:
Internet Sharing Server
Iomega Watch
Iomega Startup Options
Iomega Disk Icons
Microsoft Find Fast
Office Startup
Sharing and Mapping Software
UMAX VistaAccess

Thanks!