So you have a Virtual Server host that is not properly saving the state of the virtual machines when it reboots during planned or unplanned outages. You checked the settings of the VMs and they are properly configured to Save State when the Virtual Server host shuts down under General Properties.
So why is this happening?
Windows defines a registry value called WaitToKillServiceTimeout that defines the amount of time that the OS will wait for a service to shutdown before killing the service (force it to shutdown). If you have a virtual machine that takes a long time to shutdown, then you need to increase this value to provide enough time for the VSSRVC.EXE service to save the state of the virtual machines.
To accomplish this, follow these steps
1) Determine the new value (in milliseconds) that is required for the successful save state.
2) Start Regedit.
3) Locate, and then click the following registry subkey:
4) Right-click WaitToKillServiceTimeout, click Modify, type 90000 (or the value you determined as the minimum time in milliseconds), and then click OK.
5) Restart the host computer
Now when you shutdown the server, the virtual machines save state should be successful.
Refer to http://support.microsoft.com/kb/888745 for more information.