" 1. Has gotten very noisy (sounds like hard drive or fan??)
2. Shuts down at times, with absolutely no warning, no error messages, nothing!
3. Freezes at times, with no warning (eg: slow down), no error messages, nothing!
4. Sound disappears, and comes back eventually, again no warning etc
5. Goes into power saver (hibernation) and refuses to come out of it! Puter needs to be turned off at switch and restarted. "

Wow...sounds like my HP dv9408nr......it did all of the above.
I called HP for support because my model had known issues and the warranties were extended.
So, after calling HP 6 times and getting run through the ineffective flow charts that the Indian Support Reps use...I was finally granted permission to mail my Laptop back to HP.

They replaced my system board,keyboard,Broadcom Card and my DVD player free of charge. Perhaps there are known issues with your puter????
Well good luck....and if ya need any help.....call me...I've become quite fluent in Indian