No Login information on Windows 98

Hiya, on one of the machines in our office, there is an unusual problem. Usually when you turn on one of the machines, you will be prompted to put in your username and password and this will connect you to the network. But on this particular machineit goes straight to the Windows screen, but it is still connected to the network. In control panel, network and tcp ip address all the info is correct, but it still doesnt come up with a prompt to login.
What am I doing wrong and can someone help me to solve this pls.

Thanks