Freezes when performing "background tasks"

I have had the same protection for about a year now and recently everytime my computer goes idle and I come back to it, it is frozen. I can move cursor nut when I click something...nothing. And it doesn't stop until I reboot my computer, where I get the infamous your computer was restarted incorrectly crap. I have no idea where to begin except turn the computer off or throw it out the window. I tried putting it in sleep and logging off and same thing. What's next????