IT Core Blog

Important Hyper-V Network issues related (Recommended Updates):
KB974909 - The network connection of a running Hyper-V virtual machine is lost under heavy outgoing network traffic on a Windows Server 2008 R2-based computer
KB981836 - Network connectivity for a Windows Server 2003-based Hyper-V virtual machine is lost temporarily in Windows Server 2008 R2.
KB978309 - IPv6 transition technologies, such as ISATAP, 6to4 and Teredo do not work on a computer that is running Windows Server 2008 R2 Server core.

When this issue occurs, one or both of the following events are logged in the System log on the VM:
Event Type: Warning
Event Source: netvsc
Event Category: None
Event ID: 5
Date: <date>
Time: <time>
User: N/A
Computer: <computer name>
Description: The miniport ‘<network adapter name>’ hung.

Event Type: Warning
Event Source: netvsc
Event Category: None
Event ID: 4
Date: <date>
Time: <time>
User: N/A
Computer: <computer name>
Description: The miniport ‘<network adapter name>’ reset.

Notes:
KB979409 is to be installed in the Hyper-V servers.
KB981836 is to be installed on the Hyper-V server which will create a new set of Integration Components and then the new Integration Components will need to be updated in the Windows 2003 VMs.

KB978309 - Check Related Issues in the following posts:
IP Helper Service – IpHlpSvc Consume more than expected %CPU
“Unable to add additional node to Hyper-V Cluster”
“Windows 2008 R2 problems with HP Drivers”
“Windows 2008 R2 problems with HP Drivers Again…“

Additional Updates At:
Hyper-V Update List for Windows Server 2008 R2
Hyper-V Update List for Windows Server 2008