OS X 10.8.3 fails to load after reboot
I am having some serious troubles with my MacBook 13.3 Oct 2009 edition after updating to the latest version 10.8.3.
1: it would boot to a blackscreen and with a flashing cursor on the top left hand corner and sit there and nothing else happens.
2: rebooted Mac a few times and each time after that comes up with the following error message:
"No bootable device -- insert boot disk and press any key"
This is happening STRAIGHT after the update, I've never had such a problem like this with any of the previous updates. Something seriously went wrong with the update for this happen..
I need some help before going to Apple store (which I have already booked anyways - just incase).
I am sort of familar with the OS and Mac's but not that great with fixing errors.
Any help would be most appreciated..
Thanks..
MacBook, OS X Mountain Lion (10.8.2)