I don't see how replacing the dvd drive would solve the shutting down problem. It could be overheating because the fan is going out, that would explain the freezing and slow downs. No clue about the hibernation thing. As for the sound card, that could just have a bad connection or be on the way out. I've had a similar problem in the past.

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"BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Will he offer me his mouth? BOY: Yes. GIRL: Will he offer me his teeth? BOY: Yes. GIRL: Will he offer me his jaws? BOY: Yes. GIRL: Will he offer me his hunger? BOY: Yes. GIRL: Again, will he offer me his hunger? BOY: Yes! GIRL: Yes. BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Yes. BOY: I bet you say that to all the boys!" -Meatloaf