I am having problems running Parallels 3.0 on my MB. If I start up the VM (linked with a bootcamp partition) when using two monitors --the external one being the primary-- the performance is really bad... and all my system crash quickly (both macOS and windows) The problem desappears if: a) I do not use the external screen (i.e. working only with the MB LCD screen). and also if, b) If I start up without the external screen, even if then I plug it again, all works fine. Solution b) is quite tedious, but is better than nothing. Do you have more information about this issues? Thanks in advance, P.D. I have found this thread (http://forum.parallels.com/showthread.php?t=10467) which seems to describe the same issues, however it is a quite old thread.
Please post your build number and kernel panic log or Parallels crash log. Also what are the exact resolutions of your screens?