NO logon screen

Got a problem:

One of our LAN has a NT4.0 sp6a BDC server (DHCP, WINS, DNS) and 50 win9x clients using TCP/IP as the only protocol. All clients are configured as “client for MS network”. Everything work fine unless I tried to modify the DHCP leased period to 1 day. After that when user turns on the computer, no logon screen comes on. If I issued a ‘winipcfg /renewall’ command, the logon screen will come on. I reconfigured the DHCP leased period to 3 days (default) and the problemstill happen.

Any ideas on what the problem is and how to fix it?

Appreicate the help!