I'm using multiple virtualization products on my MacBook Pro (VirtualBox, VMware Fusion, Parallels). To avoid problems I always make sure only the procesesses/kernel extensions for one of those products are running.
For VirtualBox you can run:
sudo /Library/StartupItems/VirtualBox/VirtualBox start
sudo /Library/StartupItems/VirtualBox/VirtualBox stop
For VMware Fusion 3:
sudo /Library/Application\ Support/VMware\ Fusion/boot.sh --start
sudo /Library/Application\ Support/VMware\ Fusion/boot.sh --stop
Is there a single command or script to stop/start the Parallels stuff? Currently I am running multiple 'launchctl' and 'kextunload' commands.