Here is an update.

I have kept the Inbox empty for the past couple of days by moving
messages into another folder. Now, when I receive messages, several
will remain hidden/undisplayed. If I switch to the Unread Mail Search
Folder, and then click back to the Inbox, all of the messages show
up. I do not have to do anything else. Hence, it is clear that
OL2007 has either a database retrieval or rendering problem.

Any other ideas?

Thanks,

Gomer