RedHat 7.3 & vpn client 3.5.2 on T23

I just got an IBM T23, installed RedHat 7.3, and did up2date.

Everything is working pretty well, except that if I try to do too much at
once, I get this:

Jun 21 13:56:23 dhcp-2545-22 kernel: eepro100: wait_for_cmd_done timeout!
Jun 21 13:56:54 dhcp-2545-22 last message repeated 10 times
Jun 21 13:57:55 dhcp-2545-22 last message repeated 32 times
Jun 21 13:58:25 dhcp-2545-22 last message repeated 15 times
Jun 21 13:58:27 dhcp-2545-22 kernel: NETDEV WATCHDOG: eth0: transmit timed
out
Jun 21 13:58:27 dhcp-2545-22 kernel: eth0: Transmit timed out: status 0050 
0c80 at 30928/30988 command 200c0000.

I saw in the archive a message that suggests to disable sleep mode, but I
can't find instructions on how to do that, if that would help.

Can anyone help?

Thanks

Michael