I used to administer some 3Com switches and I saw similar problems with 10Mbps Ethernet devices. Check the errors on the switch and on the empeg (if you can -- it will be ``netstat -i'' if that command exists on the empeg). Force the switch to 10/half and it'll probably start working. I never really researched much (they were older Macs that I just got Fast Ethernet interfaces for), but I always assumed that what was happening is that the switch's autonegotiation was going nuts. When the IEEE released the Fast Ethernet spec, one of the things included was an autonegotiation feature that would help the devices figure out whenter to work in 10/half, 10/full, 100/half, or 100/full mode. I think that the 3Com switches continue to try to autonegotiate after its already figured it out.