Not sure, but here is something to try 

Forum: PCMCIA Multifunction Card Issues
Re: SocketCom ES-1000 Ethernet/RS-232 card (Brian Candler)
Date: 2000, May 26
From: David Hinds <dhinds@pcmcia.sourceforge.org>

Try setting: module "pcnet_cs" opts "use_shmem=1" in /etc/pcmcia/config.opts, to make the card use a shared memory window for packet transfers. -- Dave

Messages Inline: Outline:

1. Sorry, that's not it by Brian Candler, 2000, May 28

2. Got it!! by Brian Candler, 2000, May 31

1. Spoke too soon by Brian Candler, 2000, May 31

to: "Not sure, but here is something to try"