login registry problems

I have 2 machines on my net, one 95 and one 98se, that don’t come up with the client for microsoft networks login screen when they first start up. This is the only client we use, and it is set as the default client. After the machines start, I canlogoff, and then the login window then appears. I’m almost sure the problem resides somewhere in the registries of these machines. Does anyone know what key and value I should look for?