Restart problem after upgrading to iOS6

[fadh]

I upgraded my Macbook air and my iphone 4S to IOS6 and one day after my mac start to restart frequently giving no reason but saying restart for a problem and I either need to press any key or wait few seconds for auto restart
And my phone app started to quit while am using them and this prob didn't happened before so I am not sure is it the iOS or something else and how to check it?