Arduino Nano gives 7V on the 5V PIN! I have an Arduino Nano which is Powered by an external Power supply. This is connected with VIN and GND. The voltmeter says, there are 12,12 V

I have some components connected on the 5V PIN, which altogether draw max. 100mA
Since some of the components are not working anymore, I started measuring...

I have disconnected everything, but the Arduino Nano Power supply. (12,12V)

When I now measure GND and the 5V PIN, the Voltmeter says 6,97V! I guess this is why my components are giving up. 


But why are there 6,97 Volts all of the sudden? 
Is my Arduino broken now? 
Can I fix this?
How can this happen?
Of course the 5V regulator on the nano can be faulty. Another possibility is the 5V decoupling capacitor. If it goes open circuit the regulator will oscillate and the mean output voltage will be near half the input voltage. Most regs have a minimum decoupling cap value specified.