Slow/Unreliable network

[Kirtis Bakalarczyk]

Lately i've been having several network problems, like slow DNS
lookups as well as extremely slow ssh and subversion access.  At first
i thought it was an ipv6 problem, so i disabled the module however,
that hasn't helped (and i've since tried again with ipv6)

I'm sure it's not a problem with the NIC because it works on the
liveCD, and i'm sure it's not a router problem because other computers
on the network work fine.. (including this one a couple days ago). 
When it doesn't work fine i get the following entries in dmesg:

0000:02:09.0: tulip_stop_rxtx() failed
eth0: Setting full-duplex based on MII#1 link partner capability of 45e1.
NETDEV WATCHDOG: eth0: transmit timed out
eth0: 21140 transmit timed out, status fc340000, SIA ffffff5e 00000000 00000000
00000000, resetting...
eth0: transmit timed out, switching to MII media.
0000:02:09.0: tulip_stop_rxtx() failed
NETDEV WATCHDOG: eth0: transmit timed out

.. and then the last couple lines repeat a few times.  This problem
ranges from absolutely no network access to very slow access like I
said above.. I'm fairly certain this is a kernel problem because
that's the only thing related to networking that has changed, and it
was working before the recent kernel upgrades.  I'm at a loss for
which kernel option would cause this though.. also, i do have a
firewall enabled, but i've tried with and without it with no success.

Any suggestions appreciated..

KIRT