I’m currently using Vista x64 with a nVidia-based videocard with dual monitors and have run into the following issue:

 I work on my machine, then I lock it.  Later I come back and type my password to unlock it and I get to stare at black monitors with only the cursor showing.  Previously I would have shutdown the machine (power button does this gracefully) and then start it back up.

 Yesterday, I found a workaround while trying a bunch of different things, since I had a couple of Visual Studio 2008 instances open among other things:

1. Lock your machine again (Windows Key + L) or (Alt+Ctl+Del, then L).  At this point, you still won’t be able to see anything, but your cursor should technically be in the password box for your login.
2. Now, type your password, hit enter, and your desktop should come back they way it should have when you first unlocked it.

Update 04/04/08 - You may have to repeat these steps a couple of times to get it to work.

Annoying, but at least now I don’t have to restart my computer everytime I get the BSOD (Black Screens of Death).