Wake Monitor, No View, Just Cursor

Once again, I am compelled to guess where to post my inquiry, as I don't know what this might be about. I'm rather in the dark, along with the monitor:

For the third time over the past few weeks, when I moved the mouse to wake the monitor a short while ago, what I got was a black screen with a blinking white cursor. I can find no way to get the video part of the monitor to appear; the keyboard is somewhat active, as things such as the Caps Lock work.

Shutting down the computer, then restarting and selecting the option to restart normally works fine; that is, the usual boot process proceeds, and then my usual programs all restart correctly.

[EDIT] I meant to run sfc /scannow before posting this missive; have now run it twice, which did not report any problem(s.)

The only thing I saw in the Event Viewer was that SABKUTIL failed to load; nor overly surprising, given that a search for this driver did not find one, not even in the Device Manger with "show hidden devices" selected. The only other entry in the Event Viewer has me quite puzzled, as it refers to an unexpected system shutdown at a time that the system did not shut down; had it done so, I'd have been presented with the usual log-in screen, which was not present today until I shut the computer down to fix the blank monitor problem, and that shutdown was well over an hour after Event Viewer appears to have logged the unexpected system shut down.

Windows7 Home Premium; no new software (other than the usual updates to such as Avast!,) no new drivers, etc., since before the problem started, other than an update to Firefox 4.0 Beta 10 a few days ago--and I'm fairly sure that I was using Beta 9 when I first encountered the problem.

What do I do to try to find and fix this?