I'm running Panther on a new iMac and have it set to ask for a password when waking from sleep. Usually it wakes up with no problems. But intermittently it asks for the password and then the screen remains dark, with only the white outline of a cursor visible. If I try to type or click it usually just beeps. I wind up shutting down from the keyboard and rebooting. Rebooting doesn't always make the problem go away.
What could this be and what could I do about it?