Consider the following scenario:
- You have a Hyper-V host that is running Windows Server 2012 R2.
 - You run either a Windows Server 2012 or Windows Server 2012 R2 virtual machine (VM) on the Hyper-V host.
 
In this scenario, you receive a Stop error message that resembles the following: 
STOP: 0x0000007F (parameter1, parameter2, parameter3, parameter4)
 Notes- Stop error 0x0000007F indicates an UNEXPECTED_KERNEL_MODE_TRAP issue.
 - The parameters in this Stop error message vary depending on the configuration of the computer.
 - Not all "0x0000007F" Stop errors are caused by this issue.
 
This issue occurs if the following conditions are true:
- The VM instances are part of a network load balancing (NLB) cluster, and the time-out is set in the Extended Affinity configuration.
 - The VM instances are serving traffic across the NLB cluster IP.
 - A start or drain Stop request is submitted by either VM instance.