wrote:

Outlook 2007 will download my messages, but will not display them
all. For example, if OL2007 tells me that it has received 10
messages, only 5 will be displayed. The others are simply not shown.
They are not redirected to JunkMail or Spam folders (I have no
filtering rules, and have disabled Norton AntiSpam).

Do they appear in the Unread Mail search folder?

If I open the exact same PST file in OL2003, the messages show up
properly in the Inbox. If I move the PST file back to OL2007, they
are still hidden.

Reset your view.
--
Brian Tillman