Yep Dub and Scott are correct. And when Dub says it can be a **** to figure out, he ain't joking! Dub gives great advice in the trouble shooting process.
But on note on what CJ says about onboard sound:
He's right.
I have two boxes. On the one that has the built in Realtec sound card, I have chosen to install X2 on it, To make it work I have to use ASIO4All drivers. Otherwise X2 would not run. And here's where CJ's advice comes in: If this box was the only box I had, my first purchase would be a USB audio interface. It just ain't worth the headache. Because for some reason the drivers just go missing. And I haven't figured out why. Only a restart seems to work, sometimes! So I would not do this all the time.
Good usb audio interfaces can be had for cheap. Do yourself some good and get one.