I know OL2003 has some bugs if you don't patch it, weird things happen. I'd read https://social.technet.microsoft.com/Forums/exchange/en-US/75a282fd-3c36-49ba-9450-c4d95e6dcc59/outlook-only-showing-recurring-meetings-unless-view-is-changed?forum=exchangesvrclientslegacy and reset the panes as well as use the calendar check noted there.
Every time I enter a new appointment into Outlook calendar, it defaults to "recurring" mode. The only way around this is to set each entry to stop after 1 session which I have been doing for a year and am tired of it. Started on an XP-Pro OS and migrated to the Windows 7 on a new computer.