linksys router with comcast cable modem on 2 xp machines

I have the following setup working but its become flaky recently (wasnt so flaky before 1 week)

cable modem (comcast) to a linksys BEFSR41 4 port router with 1.44.2z firmware (dec 2002. I read somewhere this is the stable version)
I recall using the ethernet address of the router to register with the comcast modem (so it thinks that it is dealing with the router as a computer).

Recently I have been losing pings on the XP pro machines connected to the router (to the 192.168.1.1 itself.. it becomes hideously long or unreachable which is bizarre)

it resolves after a shutdown and reboot (pings again) on one of the machines.
on the other one a simple router power cycle helps (no need to reboot)
 
not sure why this behavior has surfaced recently..

my router settings are as follows:

domain name: comcast.net

for some reason the LAN IP address and the WAN connection type fields have almost the same ethernet MAC addresses..
just differs by ONE on the very last digit.  not sure what to make of this. These ethernet addresses are in small font.

none of the virus stuff is enabled

in the advanced tabs, the MAC addr clone seems to have the same address at the WAN connection type ethernet address on the opening page

working mode is as a gateway

I am not blocking WAN requests etc. as sometimes I use a VPN (right now I am not using VPN)

I wonder if my settings are correct. (well they have to be to some extent as my setup works till the recent flakiness)

Heh: I couldnt post it as I lost the connection on this machine again. no ping from router

a shutdown and reboot will enable me to post this

update:  I havent yet shutdown.. I powered on the router and it gets back the ping for the other XP machine (but not the one I work on)

something happens pretty soon and I lose pings to the router on both machines (and of course the net as well)

then when I power up the router the second machine gets back its ping and net access
the first one (which I am working on) is still finding the router unreachable.. until the reboot after which it will last for 10 minutes or so


If my prediction is correct a log off wont help matters. lets see.
the cold reboot doesnt help at all. now for shutdown and reboot

ok the shutdown works.. before i lose this let me post it.

summary:

Both XP pro machines lose ping to router which is connected to cable modem
one of them is revived when the router is powercycled
for other one a warm reboot is needed and the connection after this does not last long.

is it a NIC problem in the warm reboot machine? or is the router very old (which it is)

I can access the interface for the modem itself usine 192.168.100.1 and it contains a MAC address that seems unfamiliar (under PC connectivity). I assume this could be the MAC address for the modem itself.