No password dialog box after waking up from sleep

Sometimes when I let my MBP (see sig) go to sleep with the screen open, I come back and hit the spacebar to wake it up and it doesn't give me the password dialog box to wake it from sleep. All i see is a black screen with the mouse pointer on it. This sometimes happens when I wake and DO get the password box but if I wait and don't enter the password right away, the box disappears and wont come back. In both cases I'm forced to push the power button to shut it down and restart. Any solutions to this, or is it just a fluke?

 

Yeah I hear you about the hard rebooting, I cringe everytime I have to do that. It used to be that by closing the lid, waiting for sleep, then reopening I would get the functional box, but lately that doesnt seem to work either. I'm curious if there might be a keyboard command or something that could bring up the functional box.

 

This is happening again...no functional box to type password after sleep. I've tried closing screen and allowing to sleep numerous times to no avail. I've also let it fall asleep with the screen open and no luck. All I get is a black screen and the mouse pointer. Any ideas?