Problem with 3com 905 100TX Boomerang

Hello,

I have just installed RH7.3 up2date with kernel 2.4.20. I have two 3com 905
100TX Boomerang nics. I have connected my computer to cisco's catalyst 3548.
When the settings on switch are speed=auto, duplex=auto everything works. If
I change settings to speed=10 duplex=full, connections goes down. Even if I
change settings to /etc/modules.conf to:
options 3c59x options=0 full_duplex=1 connection is down (I have tried to
rmmod 3c59x and then restarted the connection). after reboot connection is
still down. Then I have removed options line from /etc/modules.conf and
rebooted. When server booted up connection was up. This happened several
times. Even if connection is up and I just unplug the cable and then plug it
back, it doesn't work before I reboot. when connection goes down mii-tool
shows:
No MII transiever found! or something like that I cant remember exactly
sorry. When connection became up mii-tool showed: eth0: no autonegotiation,
link up. Can you help me? Thanks in advance

Best Regards,

George