2MHz PPC G5 iMac OS 10.4.11. Several attempts were made to login with wrong password. The iMac is now frozen on the login screen. Entries can be made in the Username and Password fields, but there is no response to "return" or "cmd" keys. The action buttons (sleep, login, etc.) are grayed out. Power button only puts machine to sleep, and it wakes up at frozen login screen. Any fix for this?
