My MacBook died and won't start anymore I have a 6 year old MacBook. It suddenly died last Sunday. When I started it the battery was charged to 100% - some minutes later it was at approximately 20%. Then the screen suddenly turned black and shut down.

I wasn't able to start it again since then. It usually shows the grey screen and the progress wheel but then either remains in that state for hours or turns black again.

I tried everything from Mac OS X: Gray screen appears during startup: from safe boot, resetting the NVRAM/PRAM, to starting from installation disc. With the only result that it does not eject the disc anymore. 

As I read, everything indicates that the hard disc is broken. Is there anything else I can do than to buy a new notebook?

Update: 
- AHT didn't inspect any problems
- boot after removing the battery didn't work
so, I bought a new hard drive. installed it today and brought my MacBook back to life finally.

Did already love the idea to own a new MB Air ... maybe next year.

thx for your help guys!