Hello Milly,
Since the original poster seems to have dropped the subject, let me continue.
I am experiencing the same problem. I can read some messages, and then,
decide I want to mark one or more of them as unread. So, I go back and one by
one I right click and pick "Mark Unread". Some of them will be marked as
unread, others will not.
According to Help->About, I am running Outlook 2003 (11.8206.8202) SP3,
installed from Office Professional Edition 2003.
The email accounts involved are all POP3 accounts.
There are no error messages issued when this occurs.
I am running Outlook under Win/XP with Service Pack 3 installed, however I
believe the problem started occuring before I installed SP3.
If you need additional information, please let me know.
Thanks,
Charles