It looks like this could very well be a function of your McAfee antivirus since there is a patch for McAfee version 6.02 which deals with "Outlook Express inbox deletion issue" Here
. It may be McAfee found (or thought it found) an infected file in your inbox and quarantined the whole thing.
You can try forcing OE to use your old Inbox by, first, turning off McAfee and closing Outlook Express, then deleting the new Inbox(1). Make sure the remaining Inbox file is named Inbox.dbx. Then open Outlook Express and see if the old inbox is back.
If you do get the old inbox back, you need to find the infected file, or files, and delete them or McAfee will probably do the same thing when you start it up again.
If this doesn't work, restore the deleted Inbox(1) from the Recycle Bin and hope somebody with more experience using McAfee comes along to help.