Problems with Outlook 2000

Trying to help a friend out. He was using outlook 2000 when it started to lock up and become non-responsive. It does it when trying to send or even clicking on address book. In his impatience, he then tried outlook express 6 and made that the default mail handler, the problem is the inbox and sent items are both over 10,000 emails and deleted is 6,000 emails. So rather than just troubleshooting the original problem it has now gotten complicated by his switch to OE6. I booted in safe mode and brought up outlook and deleted about half the emails but it is still locking up. CPU goes to 100% when you try to do anything with it. Any ideas???