At some points, the computer suddenly refuses to play sound, and the only way to stop it is to restart. The sample ding at the volume control won't work (the green thing doesn't even go up), anything that waits to play sound before continuing (like media player, YouTube, etc.) won't work, and yet the computer can be perfectly fast! Why is that? Also, has anyone got that problem, too? I'd like to know another way to get it working again without having to restart. Thanks peoples.