I have a Windows Server 2003 and when trying to access one of my many computers on the network, one tells me I have to logon and it says guest then asks for a password. I know there is a way to get rid of that box but how???
It sounds like that machine may not be a member of your domain (assuming you are using one).
(Windows XP) You should be able to disable the guest account in Control Panel -> Accounts.
Start by ensuring "simple file sharing" is turned off on the client machine. If that doesn't work give us something to work with, such as some information about your network structure, whether or not you're using an AD domain, etc.