the bios fix for thermal dust is preventative in nature -- it will not help an already dust-clogged heatsink.  if you're under warranty, have the heatsink/fan assembly replaced.  if you are not under warranty, try blowing compressed air into the back exhaust vent (with the computer turned off) to see if you can knock some of the dust out.

I am not under warranty... Would it be a good idea to open the system and clean the dust accumulated?

try a can of compressed air first, it's a lot easier

what do i just blow the compressed air into the fan? will that damage my systeM?

just do what i said.  turn off the computer and blow compressed air into the back, right exhaust vent (it's where the air comes out and you should be able to see the heatsink if you look into it).  make sure the bottom intake vent is not blocked when you do this.  if you are exceptionally paranoid, you can try sticking a small object (pin) into the fan to keep it from spinning while you do this (I never have though).

 

Thnks very much.. I just blew through the vent and now my system is running good with no suspicious shutdowns.. Appreciate your help in getting me peace of mind again!!!!!