You need logs, but I’m certain your OOMKilling the host. Pay less attention to what the VM is doing, and more to what the host is doing. Passing that amount of data through a VM on a host with only 4GB of RAM sounds like it’s destined to fail. Put a hard limit on the memory the VM can use and see if that helps, but I just don’t think you have the resources to manage this in the way you’re attempting.

A better question is: if you’re only running PBS on this machine, why is it in a VM?