NIS Locking Uo Outlook 2003

I'm having trouble with NIS locking up Outlook 2003 on an XP (SP3) computer.

 

The computer previously had Zone Alarm installed.  I completely uninstalled using ZA's Cleaner app and followed up with Decrapifier, Revo Uninstaller, and CCleaner, just to be safe.

 

NIS was installed from-scratch and is version 20.3.0.36.

 

Outlook will run just fine for a while but will eventually lock up.  Clicking on any of the buttons will simply result in a short error sound.

 

I've tried running a repair installation of Outlook, but that did not fix the issue.

 

Anyone have any suggestions?

 

Many thanks.

 

Andy