linux eth0 doesn't work

Any help will be greatly appreciated.

config A) dsl-RH 7.1 (works great)
config B) dsl-linksys router (801.11a+g)-1) RH 7.1 (very slow/doesn't work)
-2)win xp wireless (works great)
-3)win 98 wired (works great)
PING:
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In case B), I can ping from 1 to 3, but the icmp_seq reported is not in
numeric order, e.g. it goes from 1,2,3,6,13,24, etc. and of course,
there is high packet loss.

ping localhost does not report any problem. No packet loss.

IFCONFIG
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ifconfig eth0 reports 738 errors out of 531 TX packets and 649 RX packets.
ifconfig lo reports no problems ; no errors

I cannot even get the setup page from the router; forget about getting
anything from internet.

Also, I had none of these problems earlier; these surfaced after I
shutdown the machine for some reason and rebooted.