[X4U] Entourage mystery

[Jan Melichar]

Entourage has been running without any problems for a number of years  
but now when I click (highlight) any item in the list in the top pane  
that item disappears  from the list while the message remains in the  
bottom pane and so becomes inaccessible the moment one moves to  
another item. I have trashed the preference file and rebuilt the  
database but to no effect.
Anyone any idea how to resolve this problem?

Jan