KB2264080 is a Hyper-V rollup that includes the fixes documented in the following KBs:

975530  Stop error message on a Windows Server 2008 R2-based computer that has the Hyper-V role installed and that uses one or more Intel CPUs that are code-named Nehalem: "0×00000101 – CLOCK_WATCHDOG_TIMEOUT"

http://support.microsoft.com/default.aspx?scid=kb;EN-US;975530

974909  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

http://support.microsoft.com/default.aspx?scid=kb;EN-US;974909

981791  "STOP: 0x0000001a" error message on a computer that has an Intel Westmere processor together with the Hyper-V role installed on Windows Server 2008 SP2 or on Windows Server 2008 R2

http://support.microsoft.com/default.aspx?scid=kb;EN-US;981791`

So three LDRs are combined into one GDR and everyone using Hyper-V R2 is advised to install this update.

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