[TYPO3] problem with domain records

[Brian Bendtsen]

Hi

I have made a site for a firm with 5 departments.

Each department has a sub domain.

When a user visits www.firm.com she will see the common page and links 
to each department.

When a user visits department1.firm.com she is directed to this 
departmens main page.

This works fine by using domain records, but I want the user to be able 
to go to the common page or any other the other departments.

I cant make this work, its like the user gets stuck in the sub domain 
and clicking a link to another department has no effect.

How do I solve this?

/Brian