Solution: When Windows XP mode does not start...

When you are unable to run Windows XP mode, which is no other than a XP virtual machine running under Virtual PC (a free Microsoft application), one of the reasons may be that the virtual hard disk has been mounted as read-only. How to solve this? Well the simplest of the solutions is to make the folder, subfolders and files, where the virtual XP machine is located, read-write using the shell command ATTRIB /S -R. However, you may run into an ugly "Acces denied" message even with elevated privileges. What to do, then? The only solution that has worked for me in virtual environments, including VMWare virtual machines, is a quick and dirty one. Simply take that unruly folder and:  1) copy it in the same disk or partition with a different name, and 2) then run the command mentioned above. It should work just fine and the read-only attribute will be cleared; 3) Try and rename the original folder (this is important); 4) Rename the copied folder with the exact name as the original. You may not need to follow these steps if you make sure to install first the Virtual PC program and then the Windows XP application that can be downloaded for free, as well. When setting up the XP virtual machine you will have to go through a similar setup process as with a hard machine, including providing a password for the administrator. For more information and to avoid any confusion, please follow this guide: Install and use Windows XP Mode in Windows 7.