I'm running Parallels Desktop 7.0.15098. When I migrated my Mac OS X 10.7.4 Lion system to a new Mac, I decided to move two Parallels virtual machines, for Windows 8 Preview and Ubuntu, to an external hard drive, and to run them from there. Now I can't get either of these virtual machines to boot up from Parallels. In each case the virtual machine, either Windows 8 or Ubuntu, starts the bootup process, but immediately throws up an error message and says it needs to reboot, and goes into an infinite loop. There are no errors from the Parallels application; the errors are from within Windows 8 and Ubuntu. Meanwhile I have another virtual machine of Windows 7 that is on the main system hard drive inside my MacBook Pro, and it runs perfectly fine under Parallels. How can I repair this? I'm on a new MacBook Pro 13-inch (mid 2012) with 4GB RAM and an internal 240GB solid-state drive. The external drive holding the Parallels virtual machines is a 7200 rpm 500GB drive connected via USB 3.0 (the new MacBooks have USB 3.0 on the motherboard).