I have Outlook 2003 and have received the same message for months. Several Google searches have listed different possible causes,i.e., related to various programs, drives, media readers, etc. Since one listed cause was that it was tied to trying to read the floppy drive, an option was to disable the drive through device manager. Instead of doing that, I tried simply inserting a floppy disk in the drive when first opening the program. That worked for me, using a Dimension 8400 running XP Pro.

You should try a Detect and Repair on the Outlook Help menu. Seems you saved an OL file to floppy a while ago and OL keeps looking for it when you open OL. Changing to a new mail profile will probably cure this. You can also try File, Open Outlook Data File and open your original pst file.