My MacBook Air 2008 Model A1237's volume is not working. When I press the volume buttons it comes up with a grey circle with a cross through it. In settings under sound, it says "no output devices found" and also "no input devices found". After researching it, I decided to reset the NVRAM. I tried this and after a few tries, I reset my NVRAM and my volume went back to normal. After a couple minutes of using it, my volume stopped working again. Since then, I have tried and tried to reset the NVRAM (using all of the steps on this website: http://support.apple.com/en-au/HT204063) again, but it is not working. When I am simultaneously holding down Command, Option, P and R and have just switched on the computer, the screen goes from black to grey to black and so on. I have tried letting go of the keys when it goes to a grey screen and this has not worked (it has just started up normally). Any help would be much appreciated.
Processor speed - 1.8 GHz
Memory - 2GB
Storage capacity - 60GB
Version - Mac OS X 10.6.8 (as my computer is too old to update to Yosemite).
Processor speed - 1.8 GHz
Memory - 2GB
Storage capacity - 60GB
Version - Mac OS X 10.6.8 (as my computer is too old to update to Yosemite).
