Parallels Black Screen of Death
I have a MacBook Pro, running Parallels version 2.5, build 3214.0, with Windows XP loaded into Parallels.
I experienced a black screen when attempting to load Parallels, too. I'd get to the loading Windows XP screen, then all went black. I read an online thread somewhere that it may be related to screen resolution conflicts between Windows and the Mac.
I decided to try quiting (you may need to force quit) parallels and change my screen resolution on my MacBook Pro to 1280 x 800. I then relaunched Parallels. I still got the black screen, however, I was able to access the Parallels Mac menus. I selected Parallel preferences, selected the general tab, and changed the "what to do when quitting" option to, "ask me everytime". I closed the preferences and quit Parallels (Apple key plus Q).
I was happy to see the question, "Suspend, or Stop machine". I selected stop machine. Windows shut down properly. I then relaunched Parallels and the black screen was GONE.
I had full functions back. It seems the screen resolution on Parallels and the Mac totally cluster fluxed the boot up process. At least that seems to have been my issue. I can't say for sure it will be everyone's issue, but it's worth trying what I did, it only took me 10 or 15 minutes. I've read many people have spent sleepless nights due the a Parallel black screen of death.
Good luck!