Machine check exception
Machine check exception is when you see something like this in your logs:
Jul 9 12:19:41 vz01 kernel: CPU 0: Machine Check Exception: 0000000000000004 Jul 9 12:19:41 vz01 kernel: Bank 4: b604a00100000813 at 000000007e4f2f68 Jul 9 12:19:41 vz01 kernel: Kernel panic: CPU context corrupt
What does that mean?
Such messages are printed when CPU reports about detected hardware problems, e.g. memory corruptions or some other problems. It is 100% hardware problem with your server.
What to do?
The best thing to do is check your server — see Hardware testing.