Retrieving Mail from exchange server

[Aranox]

This is my first post, so i hope its in the right spot. On to the question.

We run a exchange server, and all the PC's connect through outlook 2003 to it. A user got a new PC, and when we set up outlook, it would not retrieve all her old emails, only new ones recieved since setting it up on the new PC. When you look on the server itself you can see that all the messages are indeed still on the server. Everything is set up through AD, and we've never had this problem before, even when giving users a new pc. Any ideas/suggestions on how to convince the server to deliver all her old messages back to her outlook inbox?