I just had an odd thing happen with a Hyper-V server that has 4 guest VMS running on it. The host server and all guests are Server 2008 R2 SP1.
I logged into one of the guest VMs using Remote Desktop and rebooted a web application running on it, then logged out. I tried to access that service remotely and it was unresponsive. I tried other services and they were unresponsive too. I logged into the host server and opened the Hyper-V console, and all of the VMs were paused. WTF? I manually resumed them and off they went.
I'm pretty sure I didn't do anything to make those VMs pause. One I may hove done accidentally somehow, but a bunch of 4, definitely not! So how could this have happened? What would make VMs pause themselves?