My computer gets no audio all of a sudden, and it happens all the time. However, sometimes when that happens, I press ctrl+alt+del then the audio will come back immediately. Sometimes it won't work, so I have to restart the computer to get the audio back. I tried to keep track of what causes that happen, but it seems to me it's all random. Is there any way to fix it? It gets quite annoying sometimes. [i'm uing vista on a acer computer]