Hi Mark, thanks for getting involved.
I used http://www.insideoe.com/files/wab.htm
to find out where my wab file is located. I deleted it, replaced it with a older version but Outlook Express 6 still produced the message "encountered a problem, need to shutdown" after approx 30 secs.
I read http://sillydog.org/mshidden.php
but it was for ie5 users.
I downloaded Accurate Outlook Express Mail Expert to recover emails. I recovered several emails but ... And it was the trial version with options disabled.
Do you know how to locate dbx files? I believe they are associated with each of the folders in Outlook Express.