Macbook restarts when trying to shutdown

Hi all,

So i've got a macbook air, and every time I try to shutdown through the apple menu, it will turn off and then restart. Very annoying!! The only way of completely shutting down is holding the power button down, which I know isn't healthy at all.

I'm running the latest version of Mavericks and so far have tried reinstalling Mavericks and also a PRAM reset, but with no luck. Any ideas anyone?

Thanks!