What triggers the problem?  Does it "unnegotiate" after it's been up a
while?  What happens if you "hard wire" the switch/hub to always do
100-fdx?  Can you reset the card with a warm start or does it always
require power cycling?
If"hard wiring" the switch port to 100-fdx prevents the card from spinning
out of control, then you could add the necessary lines to //etc/netstart,
or what ever it's called now, to switch the card into 100-fdx mode without
worrying about the auto-negotiation, which is stil, in my opinion, not
quite ready for prime time.
-Brian
On Jun 15,  7:09pm, Jeff Northon wrote:
} Subject: Problems with ex0 on 1.4 3Com905
} Hi,
} 
} We are looking into problems with 3Com905 cards that seem to loose the
} ability to autosence the media they are attached to. It looks like a part
} of the chipset exphy0 gets hosed and then the card just "Dumbs Down" 
} 
} With exphy0 in place:
} 
} A piece from messages:
} 
} Jun 11 12:55:40 www3 /netbsd: ex0 at pci0 dev 11 function 0: 3Com
} 3c905B-TX 10/100 Ethernet
} Jun 11 12:55:40 www3 /netbsd: ex0: interrupting at irq 10
} Jun 11 12:55:40 www3 /netbsd: ex0: MAC address 00:50:04:71:f0:8c
} Jun 11 12:55:40 www3 /netbsd: exphy0 at ex0 phy 24: 3Com internal media
} interface
} Jun 11 12:55:40 www3 /netbsd: exphy0: 10baseT, 10baseT-FDX, 100baseTX,
} 100baseTX-FDX, auto
} 
} After the "problem"
} 
} Jun 14 01:18:47 www3 /netbsd: ex0 at pci0 dev 9 function 0: 3Com 
} 3c905B-FDX 10/100 Ethernet
} Jun 14 01:18:47 www3 /netbsd: ex0: interrupting at irq 11
} Jun 14 01:18:47 www3 /netbsd: ex0: MAC address 00:50:04:a5:6e:75
} 
} What now?
} 
} Jeff Northon
} 
} 
>-- End of excerpt from Jeff Northon