Microsoft has delivered a hotfix designed to resolve an issue in which virtual machines running in Hyper-V on top of Windows Server 2008 R2 are impacted by severe network instability. “You install the Hyper-V role on a computer that is running Windows Server 2008 R2. You run a virtual machine on the computer. You use a network adapter on the virtual machine to access a network. You establish many concurrent network connections, or there is heavy outgoing network traffic. In this scenario, the network connection on the virtual machine may be lost. Additionally, the network adapter is disabled,” Microsoft informed via KB974909. Download and apply this hotfix only to systems that’re experiencing the problem described [above]. This hotfix might receive additional testing.