One incident is a co-incidence. Two is a pattern. For the second time I dealt with a strange situation that did not seem to adhere to any predictability other than the fact that it will happen. Sometime. A Windows 2008 Server Core and now a Windows 2008 R2 Enterprise Server with Hyper-V and some virtual machines would run fine for days, then suddenly become unresponsive. The machine is up, Hyper-V VM's are inaccessible, console is locked up, can telnet to SMTP service but for the most part the system is dead. Only a hard reset helped. Until the next time.

The way I fixed the Server Core issue, and hopefully the R2 incident, is by configuring Hyper-V's network settings as follow:

• Since my servers each had two NICs, I configured one for the host OS called LAN, and the other for Hyper-V's exclusive use.
• The LAN interface is the one used to access the host itself.
• The Hyper-V interface is used exclusively for each VM.

• Ensure the "Allow management operating system to share this network adapter" setting is OFF.

  

Using those settings, ensuring the Hyper-V nodes do NOT share the host LAN interface, seem to have fixed the crashing issue.