Microsoft Virtual PC synchronizes the time between the guest and host operating systems. This is great until you have the need to set the clock forward or backwards in your VM, as it snaps back to the current time after about 5 seconds.
I went hunting through the options in the Virtual PC UI but didn’t find anything related to disabling this option. A bit of googling later and I’ve got it disabled by adding a few lines of XML to the .vmc file.
First, make sure your VM is shut down and Virtual PC is closed.
Then find your .vmc file and open it in a text editor such as Notepad. By default, Virtual PC creates .vmc files in My DocumentsMy Virtual Machines.
</microsoft> tag and insert the following lines directly above it:
Then Open Virtual PC, start your VM and you’re all done!
This was tested on Windows Vista 6.0.6001, SP1 using Microsoft Virtual PC 2007 (220.127.116.11)