Hyper-V Program Manager
As I mentioned here: - Virtual PC supports the ability to change the guest resolution by resizing the virtual machine window (rather than changing the resolution through the standard dialogues). This is a very cool feature - but one of the problems that we encountered with this feature is that programs that set their own resolutions (like games) tended to behave badly (or even crash) when we changed the resolution underneath them.
To deal with this - we added some simple logic - if the guest changes the resolution of its own accord, other than through the Windows resolution setting panel, Virtual PC disables this feature in order to maintain compatibility. Unfortunately - there is no real way for us to know that it is 'safe' again so this feature will then be disabled until we detect that the virtual machine has been restarted.