XP in a seperate domain

I have had trouble joining a domain across the intranet from a seperate domain in NT4 environment using an XP machine. Using a 98 box you can specify the domain even if it can’t be found initially. With the XP machine, if you join the domain with the domain that you wish to login to it finds it fine and you can then go anywhere within the intranet and login into the original domain with no problems. Once you change domains and try to go back to the original domain from outside that domain, Ican never get back in. I have added lines into the LMHOSTS file pointing to the original domain and also tried various intranet DNS servers with no success. Is there a way to change the domain that you wish to join without actually joining it until you logon on?