Outlook crashing after domain migration

My company has just migrated from NT4 domain controller to Win 2003 domain controller. We migrated individual user PC to connect to this new Win 2003 domain controller. XP users are doing fine. Win 2000 clients however, have issues with outlook 2000.

Outlook 2000 (internet only, not through exchange) will send and receive emails fine for the first few minutes. Then after a while, it will crash while trying to send email. I cannot stop the process through the Task Manager. And I cannot restart the PC. The only way I could do it is to push and hold down the power button.

When Outlook crashes, Internet explorer also stops being connected to the Internet. But the connection to the INTRAnet is fine.

Anybody has any ideas??