This behavior can occur for any of the following reasons:
Your password list (.pwl) file is damaged.
A service or program that loads during the startup process conflicts with another service or program.
You are using user profiles.
There is a hardware conflict on your computer.
A hardware driver on your computer is missing or damaged.
If profiles are enabled, Windows may not be able to contact the primary domain controller's Netlogon share when looking for a Config.pol file. (Windows checks for a Config.pol file even if policies are not used.)
Your primary domain controller (PDC) is not local to your Windows 95/Windows 98 clients.
A single user profile is corrupted.
Your network adapter is not correctly seated.
You are using a reserved word for your user name.
See the following link for the appropriate resolution:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q178084
(REMOVE SPACES from the pasted URL.)
Good luck,
Maxwell