I ran Compressor on an XP VM running under the OS X beta 6. The progress bar got to 100% and this message was syslogged: Unknown kernel message received. Original message text: CVirtualMachine::VmSendAbsMouse() VM paused now! Unfortunately it also popped up in what appears to be a modal dialog behind the "Compacting virtual hard disk" dialog. The error dialog cannot be activated; the progress dialog's cancel button does nothing. I attempted to use System UI scripting to close both dialogs but one ignored the event and the other rejected it. After force-quitting Parallels (kill -HUP and a regular kill had no effect) my XP VM appears to be running normally but the hard drive is still almost full (XP + updates will require 4GB if you forgot to slipstream SP2 into your install CD).