I dont know for sure, but i know photoshop keeps a list of recently opened files in a cache or something. Maybe it has to do with making sure the "hard disk/removable hard disk" actually exists...? If nothings in the drive, then it doesn't exist really... maybe that's why? Try opening and closing a bunch of files until the file you opened from the floppy is no longer in the list, restart PS and see what happens? I'd double check 'cept i have no floppies.