Symptoms
Windows XP, Vista or Windows 7 regularly asks to be reactivated both in BootCamp natively or in a BootCamp-based virtual machine in Parallels Desktop 6 for Mac.Available Workarounds
The Parallels Development Team is aware of this issue and is working on a fix.In the meantime, you can use one of these two workarounds:
Option 1.
If you have two separate Microsoft Windows license keys, you can use one to activate Windows in BootCamp and another to do it in the virtual machine.
Option 2.
1) Update Parallels Desktop for Mac to the latest build:
For Parallels Desktop 7: Download and install Parallels Desktop 7 for Mac Build 7.0.15050.
For Parallels Desktop 6: Download and install Parallels Desktop 6 for Mac from this article:
5802 Download links for Parallels Desktop and Transporter products (versions 2.5, 3, 4, 5 and 6)
2) Start your virtual machine based on a BootCamp partition. Install Parallels Tools. Reinstall Parallels Tools if it's already installed.3) Activate Windows in Virtual Machine and restart Windows. Make sure Windows is activated in Virtual Machine.
4) Restart your Mac and boot to BootCamp directly. Go to Control Panel -> System -> Activate now -> Activate online. If it does not work, try steps 1, 2 and 3 again. If it cannot be activated online - call Microsoft and activate Windows by phone, tell Microsoft support you have changes the hardware and need to reactivate Windows installed on your drive . Microsoft should not require using a separate Windows license key for a virtual machine based on BootCamp partition. Reboot Windows in Boot Camp. Make sure Windows is activated.
This solution will prevent the reactivation request in Bootcamp and in the Virtual Machine.
NOTE: If you have non Boot Camp based virtual machine, please refer tot he KB 113879.