Outlook XP Problems

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Hi,
We've been having a problem with people using Office XP this morning. Outlook will bring up and if you compose a message, and click on the to: box then it will lock up and give the error message "A fatal error has occurred in Outlook. THe data in your envelope has been lost, but your document is still available." If you try to type in the email address and send it then it just will freeze up and close.
We have tried doing a restore point on the computer, uninstalling and reinstalling Office XP, but with no luck. No searches on line have helped out either. This also happened right after an update from Microsoft Windows, but not sure if that is just coincidence.
Any ideas
Thanx
dj

 

Tried that, still not working so we are having to use web based email till we figure it out.
DJ