I'm using a Lenovo Ideapad Z560 with Windows 7 and whatever sound device it came with. The headphones work fine, but the laptop's speakers don't work unless I put the computer to sleep and turn it on again. And even then, they only work for about two minutes before they shut off again. I checked the Volume Mixer and the speakers are on and apparently playing sound, so I'm not sure what the problem is. Plugging and unplugging the headphones doesn't work; it seems that the computer is able to register when the headphones are plugged in, so that's not it. Any idea?