Outlook 2002

I have a very strange problem with one user. We are using exchange server 2000. When she sends an E-Mail to 1 person it works fine. 2 people fine. A group also works. When she sends to 3 or more people it will freeze for 10 – 15 seconds and thena window will pop up showing that it is looking for our old server. The old server is no longer in use. I have unstalled the product and re-installed it. Her name is verified on the new server. The POP3 settings all pass their test, but the problem is with inner office. I have also changed all references to the old server to the new server in the registry. Any ideas?