Could be a duplicate IP addy as well. Did you assign any of them manualy? From a command prompt just type in 'ipconfig' and check what comes up on each. I am also a bit wary of the new one having a 10Mbps card - If you have a hub somewhere in there then it will run the whole thing at the slowest speed. If some of the cards are hard set at 100Mbps that will compound problems as well. If you are using DHCP to assign addies then Bernard could well be right. Although most I have seen will allocate the full compliment of 253 addies unless you chose to exclude some.

Good luck and keep us posted.

Dave