ppp fails upon TCP connection

Under both RH8, and latest Fedora, I have same problem:
I am able to connect via ppp (using kpppd) to ISP att.net, and am
assigned IP/DNS info correctly.
After I connect, I am able to ping various hosts/sites by name (UDP
for name lookups, and ICMP ok).
The instant I attempt to make a TCP connection (surf, ssh to host on
Internet, etc) my connectivity dies. No messages show up in
/var/log/messages at time of failure. My ability to resolve or ping
any host or IP will then immediately stop working.
If I terminate my PPP connection and start another, I'm again able to
ping and do lookups. But it will fail again as soon as I try anything
TCP.

I am at:

kppp-3.0.5a-1
ppp-2.4.1-7
kernel 2.4.18-14

entries in /var/log/messages for ppp:

Mar 7 03:19:12 infrared kernel: PCI: Found IRQ 11 for device 00:0c.0
Mar 7 03:19:12 infrared kernel: PCI: Sharing IRQ 11 with 00:08.0
Mar 7 03:19:43 infrared modprobe: modprobe: Can't locate module ppp0
Mar 7 03:19:43 infrared modprobe: modprobe: Can't locate module ppp0
Mar 7 03:19:43 infrared pppd[1426]: pppd 2.4.1 started by root, uid 0
Mar 7 03:19:43 infrared pppd[1426]: Using interface ppp0
Mar 7 03:19:43 infrared pppd[1426]: Connect: ppp0 <--> /dev/536ep
Mar 7 03:19:43 infrared /etc/hotplug/net.agent: assuming ppp0 is
already up
Mar 7 03:19:44 infrared pppd[1426]: Remote message: ^@
Mar 7 03:19:44 infrared modprobe: modprobe: Can't locate module
ppp-compress-21
Mar 7 03:19:44 infrared modprobe: modprobe: Can't locate module
ppp-compress-21
Mar 7 03:19:45 infrared pppd[1426]: local IP address 12.74.56.61
Mar 7 03:19:45 infrared pppd[1426]: remote IP address 199.69.68.44
Mar 7 03:19:45 infrared pppd[1426]: primary DNS address
204.127.129.2
Mar 7 03:19:45 infrared pppd[1426]: secondary DNS address
12.102.244.2
Mar 7 03:22:54 infrared pppd[1426]: Terminating on signal 15.
Mar 7 03:23:01 infrared pppd[1426]: Connection terminated.
Mar 7 03:23:01 infrared pppd[1426]: Connect time 3.2 minutes.
Mar 7 03:23:01 infrared pppd[1426]: Sent 6903 bytes, received 8623
bytes.
Mar 7 03:23:01 infrared pppd[1426]: Exit.
Mar 7 03:23:01 infrared /etc/hotplug/net.agent: NET unregister event
not supported


The 'ppp-compress' made me try something I read where someone else had
a similar problem as I had (no tcp) but I don't think their problem
caused all connectivity to die when tcp was attempted. The person was
instructed to add 'noauth' to /etc/ppp/options, and/or 'opts novj' to
the pppd options when starting pppd (Disable Van Jacobson style TCP/IP
header compression in both the transmit and the receive direction.)
I tried all variations on the above 2 with no success.

Any help would be appreciated.

Thanks!