my 2008 macbook air wont boot up properly

My 2008 macbook air will turn on, and then go to the apple screen with the loading wheel, but after a few minutes of loading it just shuts down...



Here is an update of the problem after i messed around with it for a bit.


I start up the macbook while holding Command+s

Then it brings up the prompt.

I then type: /sbin/fsck -fy

It then outputs a message saying:

disk0s2: I/0 error.

Invalid sibling link

(4, 42746)

**The volume macintosh HD could not be repaired.

/dev/rdisk0s2 (hfs) EXITED WITH SIGNAL 8

After that, i type in: /sbin/mount -uw /

Then I type: exit

It runs the logout scripts and then immedietly boots up fine, like the computer has no problem.


It works fine like this, but i dont want to have to do those steps every time I want to use my macbook...


Any help on how to fix this?

Boot into single user mode and type in fsck -y
If it says file system has been modified, keep repeating. After that type fsck -fy
If that fails then hold down F2 then power on your macbook and do a hardware test