I'm still having some issues with Parallels 8 for Mac, latest build running Windows 8. (1) on boot up I still get a black screen for a period of time and the total boot times is still over forty seconds. 2011 i5 iMac with 8 gig of RAM - 2 gig devoted to VM plus single core. (2) still struggling getting back to start screen from Desktop i.e. pushing mouse into bottom left hand corner is very hit and miss.
Please follow the steps in this KB article to get it fixed - http://kb.parallels.com/112091 Do you use trackpad? This might be the case: http://kb.parallels.com/115040