Same Problem in Parallels 6, latest update, OSX 10.6.8. Problem submitted ID #9858241 (maybe 9858317 - it asked me to submit again because it couldn't connect because I killed prl_disp_service). Rebooting my system "fixed" it, but can't keep rebooting to correct a problem.
Build 6.0.12094
(Revision 676494; July 13, 2011)