[Q] Freezing and black screen issues!

Hi,

I am using Galaxy Note N7000 for the past 1 year. (OFFICIAL ROM)

I am facing a strange issue since the day I bought this phone... The screen goes black suddenly (this could happen even if the phone is not touched for 3 to 4 hrs. Don't know why this happens) and freezes. If i press any button , the screen will not wake up. During this time, if someone calls me then I will not get any ring, but the other party who calls me gets the ring tone that my phone is ringing. The only way to bring up my phone is , i need to press the power button still the phone reboots.

I tried factory reset twice (both gui mode and the other with Volume UP+HOME+power button)
I tried Wipe cache memory many times.

Pls let me know .. how to get rid of this issue. Should I need to use some other rom. If so pls advice.

I am ready to do any thing to get this phone to work properly.

Regards,
Dennis