SMTP connector Problem

I am moving the IMS from exchange 5.5 to exchange 2000. My exchange enviroment has two administrative groups and one IMS. The IMS is in admin group A. Once the move is completed everything works fine for mail boxes in admin group B. The problem I have is for the admin group A all email goes to the queue of the SMTP connector even if it is for the internal domain x.com. Has anyone seen this issue before? Users in admin group A can send email to users in admin group B and they get the message. Useres in group B can send and recieve messages from external domains. Users in Group A can not send or recieve any email, as all this mail just queues up in the SMTP connector.