parralells/outlook, adding additional mailbox

I have a user that is running parrallels on a mac powerbook G5. They have set up outlook 2k3 connecting to our exchange server. When i add an additional mailbox to their account. It displays in the folder listing but will not expand and will deny access. All rights have been given and this works correctly when doing the same thing from a winxp workstation logged in on the users exchange account when the same additional mailbox is being added. Has anyone tried this with parrallels. Thanks