Compacting messages in Outlook for Mac: Inbox gone!

My colleague at work was getting the Error -34 in Outlook Express 5 for Mac (OS 9.1). I suspected that she was nearing the 2GB data mark. She was.

I restarted Outlook Express and pressed OPTION. I then followed the options to compress the e-mail database.

A 2GB file (Old Messages) was created in the Documents/Microsoft User Data/Identity sub-directory. The regular “Messages” file was about 1GB.

When we checked you Inbox, all her messages were gone! The other folders that she had created seemed unaffected. All the messages were still there.

So, here are my questions:

1/ Why did the Inbox messages disappear, while the other ones did not (as far as we can tell).

2/ How does one “re-import” the giant “Old Messages” file?

3/ Is there any way to see if that “Old Messages” file includes all the old emails, including the (now) missing Inbox?

4/ Assuming I can bring back the Old Messages file, should I create a new identity and bring the Old Messages file into the new identity?

Thanks for the help!