No login prompt for Win98 computer.

I have a Win98 computer on a standard Win NT network (TCP/IP) that when it boots up and windows starts, it goes right to the desktop instead of displaying the 3-field NT network login prompt. All network settings are configured correctly and I’ve even compared registry settings with other Win98 clients. No luck. Network services are: Client for MS Network, 3Com adapter, TCP/IP protocol, and File and Print sharing for MS networks. Win98 Users applet in Control Panel has users identified andthey have passwords set to their Windows profile. Any ideas?