System Event 3012 at PDC

My NT 4.0 100mbs Ethernet single domain network consists of a PDC, a BDC and 30 workstation desktops (about half are Win95, the remaining half are NT 4.0 Workstations).
Periodically, on the PDC Event Viewer, I am getting Event 3012 RDR complaints (An unexpected Network Error has occurred on the virtual circuit to (workstation computer name). There will be one complaint line for EVERY WIN95 computer currently logged on to the network. NO complaints on ANY of the WINNT machines. Typically about half of the Win95 complaints are logged and the remaining half get logged about 10 minutes later.
Any clues as to what is happening here?
Thank You