NIC/Hub conflict

We have AMD NIC (PCnet FAST) onboard Gateway E-1000s. Recently we upgraded the management software on our Synoptics Management Modules for the 10bT concentrators. Now the AMD NICs will not connect to the network through the concentrators. So far the only fix we’ve discovered is installing 3Com NICs in each machine, but we will not be able to do this for every PC. Has anyone run across this problem, and what was the fix used? Does anyone know of manual settings for the E-1000s’ AMD NIC?