Worked like a dream for the last 4 months. Today, for the first time ever, I got the "You must restart" message. Numerous bad things have happpened since that message- repeated crashes of Surfari (this is sent using FireFox), cursor lockups, and several other forced restarts. The cursor frequently shows with two vertical purple lines. Nothing seems to be reported as wrong in System Profiler. Possibile explanations: (1)it's too hot in my house- this is the hottest day since I've owned it and it's about 86 F in this room; (2) I installed the new QuickTime update last night; (3) Other ideas? Suggestions welcome. Thanks.