Strange Switch Problem

We just purchased 3 Netgear fsm726s switches. When I moved the servers over to the new switches none of the servers would log onto the PDC, they kept reporting that a domain controller could not be found. Yet all the client PC’s (Win98) could log onto the PDC just fine. They (servers) are all running NT4 with SP6. Now when I placed the PDC and the 3 other servers onto a seperate switch and hooked that switch into one of the new switches ports they all logged on fine. Any ideas?