I'm pretty sure that this is an Outlook 2003 client problem, but since the client is talking to an Exchange 2003 server, I figured I'd ask my question here...
I just upgraded a W2K Pro SP4 computer from Office 2000 to Office 2003 SP1. Under Outlook 2000, I had setup an archive forlder. After the conversion to 2003, the archive file was still in the old format and I knew it was going to grow beyond the limits of that format. So I created a new PST in 2003 format and copied the mail from the old file to the new file. I then "tried a trick", quiting out of Outlook, renaming the old file to archieve-old.pst and renaming the new file to archive.pst.
I then went back into Outlook and found that my trick backfired. I had three personal folders, all called "Personal Folders". So I went into Data File Management and found only one entry, for the new archive file. I tested what would happen when I changed the name under Settings and found that one of the Personal Folders changed names. I then dropped that entry from the Data File Management.
Summary of what I have: No entries in the Data File Management and two personal folders, one called "Archive Folders" and the other called Personal Folders.
And I don't see anything jumping out at me in the registry.