Hard Fault on Cortex M0

I am using a nRF51422 from Nordic Semiconductor with has an ARM Cortex M0 CPU.

While trying to use their Bluetooth Mesh SDK I get a Hard Fault.

I am trying to debug the example code to figure out what the problem is, and i am wondering under what circumstances a hard fault occurs?

I have a suspicion it might be an interrupt or watch dog timer causing the fault, as it is not generated at the exact same time when running the program multiple times. 

But mostly my problem is not knowing what can cause a hard fault.