user is unable to view task lists in public folders
 

I have a strange problem:

AD, Exchange2003, outlook2003.
I have 1 user (out of 60) that is not able to see task lists in public
folders. His own task list is not a problem, all other folders where he has
permissions in the public folders are no problem. But if there is a taks list
under public folders he gets a message, that his permissions are not
sufficient to see the contents of the folder.
In OWA though, he can see all public folders with no errors.
So I suspect this to be some setting in Outlook, but I cannot fidn what is
the culprit. Somebvody ever seen this and know of a way out?

TIA
Leen