Hour-long shutdown duration “shutting down hyper-v virtual machine management service”

I have a Windows 2008 R2 server that is a Hyper-V host (Dell PowerEdge T300). Today for the first time I encountered an odd situation; i lost connection with one of the guest machines but logging on physically it seems the guest OS is still running but no longer contactable via the network.

I tried to shut down the guest machine (Windows XP) but it would not shut down, getting stuck in a "Not responding" dialog box that cannot be dismissed. I used the Hyper-V management console to reset the machine and it could not get out of resetting state.

I tried to save another Windows 2003 guest machine, and it would be progress with its Saving state (0%). The other running Windows 2003 guest was stuck in the logon dialog.

My first suspicion is perhaps one of the Windows update patches this week (10 Nov 2011) may something to do with it, which was still pending a system restart. Well, since I could not do anything with Hyper-V i proceeded with the Windows Update restart, and now it is stuck half an hour at

"Shutting down hyper-v virtual machine management service"

Prior to restarting I did not observe any hard disk errors reported in the system event log; doubt it is a disk-related condition.

Shall I force a hard reboot?

UPDATE

Ok so i left it hanging over an hour while attending to other matters, and thankfully the host cleanly restarted. I can operate the guest machines fine now. Phew.

Hyper-V must have been crawling for some reason. The VMs have been observed to become slow in the past when the host has been up for a long duration (two weeks to a month), but never this slow. Would love to know what types of performance monitoring items i can observe to give a hint why this can happen.

UPDATE 2012-02-13

In the months ever since, Hyper-V has stalled into this state another two times. It appears so randomly and without any error event logs to hint what is causing it enter this "drunkard" state. Just an Hyper-V management service timeout.

Log Name:      System
Source:        Service Control Manager
Date:          13/2/2012 9:16:48 AM
Event ID:      7043
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      elune
Description:
The Hyper-V Virtual Machine Management service did not shut down properly after receiving a preshutdown control.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Service Control Manager" Guid="{555908d1-a6d7-4695-8e1e-26931d2012f4}" EventSourceName="Service Control Manager" />
    <EventID Qualifiers="49152">7043</EventID>
    <Version>0</Version>
    <Level>2</Level>
    <Task>0</Task>
    <Opcode>0</Opcode>
    <Keywords>0x8080000000000000</Keywords>
    <TimeCreated SystemTime="2012-02-13T01:16:48.882901900Z" />
    <EventRecordID>567844</EventRecordID>
    <Correlation />
    <Execution ProcessID="764" ThreadID="8484" />
    <Channel>System</Channel>
    <Computer>elune</Computer>
    <Security />
  </System>
  <EventData>
    <Data Name="param1">Hyper-V Virtual Machine Management</Data>
  </EventData>
</Event>

The only means out of it is to restart the system.

UPDATE
This problem may never be answered given that I have recently nuked the server and installed Windows Server 2012 R2 afresh.