I think I may have had this one other time, but I don't recall. If so, the problem corrected itself somehow. Upon restarting my computer today (Power Mac G4 450, 10.4.9), after the progress bar completes on the starting up OS X screen, it proceeds to the following screen: I do not have multiple users set up, or anything set up for a login to be prompted; it should boot directly to the desktop. I have entered my known user name and password, and tried all other combinations I would ever use, but it doesn't accept. I have tried resetting the password from the Tiger disk, but still no change. Does anyone know how to possibly get past this? Thanks.