I have a Windows 2008 R2 server with the Hyper-V role installed.
I am running 3 virtual machines on this server connected to 2 virtual switches and one network port is used for Administration.
Occasionally one the machines will suddenly stop appearing on the network. I am unable to ping the machines and I am unable to ping a network machine from one of the virtual machines. They do not all stop working at the same time. In fact, I have two machines connected to the same virtual switch and one will stop working while the other one works just fine.
I have tried disable/enabling the adapter on the virtual machine. I have tried moving the machine to the second virtual switch to no avail. My only option is to reboot the machine.
I can find nothing in the event logs that give me any clue as to the problem.