Macbook keeps restarting

My Macbook Air is extremely buggy, a problem I've raised here before but haven't been able to fix so far (see here). There are just a number of bugs that keep recurring more or less randomly, which makes life difficult for me.

Recently, the computer started rebooting itself when I turn it on in the morning. There'll be a message that reads "Your computer has restarted because of a problem" in several languages, it will restart, and that'll be that. No further explanation. It says it's sending things to Apple for diagnostics purposes, but that message also only says that there is "a problem" and nothing more.

Where can I go to get this fixed? Should I just go to an Apple store and have them take a look at it? It's well within the warranty.