black screen when returning from sleep

[builder22]

if my pc has been left on long enough to go in to sleep mode all I get is a black screen when I click the mouse to return it from sleep
the monitor is getting a signal, it says so in the input menu thing, 1920*1200 active digital etc

if i press the reset button on the front of the pc this just makes it shutdown
when I switch it on again there is still this black screen (monitor still recieving a signal tho). I then press the reset button again and the pc shuts itself down once more
THEN when I restart it everything works as normal, until it goes in to sleep mode again
each time I restart the pc all the bios stuff shows up, not until windows tries to start that the blank screen happens

that is the process I have to follow to get a display after it has been in sleep mode, it never used to do this, just started doing it a few days ago

I have tried updating the graphics driver
it's running windows 8, gtx 470 card, e8400 cpu, ip35 pro motherboard

any suggestions to this strange (but consistent) problem ?

 

[RetiredGreyFox]

Hmm, I must have had this exact problem for a long time but sometimes it does and most times it doesn't.
I came on my PC about 45 minutes ago and was greeted with black screens and no amount of keyboard banging will bring it out so I have to press the reset button and get through the 'Windows didn't shut down properly' screen.
I have no idea why it does it.