Hi all. I'm having several issues related to users in my farm (mostly service accounts, as it isn't in production yet). The farm is based on W2003 servers (except SQL which uses Windows 2008) 

Domain is named sp.test.com , but when I create a web application that doesn't share the same domain name, the users are prompted to type for username and password, first try is a error because it search the user on the other domain, and in the second one I'm able to type the correct domain.

I'll try to summarize

Domain name: sp.test.com

Web Application name: shop.mall.net (I leave the host header in blank so I can access directly with that address)

First try it only prompts for user/pass and returns an error no matter which combination of domain user and password I type. Second try by default I see the username by default is shop.mall.net\sharepointadmin , and not sp.test.com\sharepointadmin which is where the user is stored in AD. I think this is also related with the SSP as it says it cannot find the username for provisioning account despite it exists in AD, but SSP is on a Web Application that doesn't share domain name with the domain.

Thank you all in advance.

PS.- First time I posted on technet, sorry for not being clear or any mistake I could have made.