Issue with audio & Limewire(?)

Some background info: Started getting into computers a few months ago, so I know the ins and outs, but I'm still a rookie. I've built my own computer and everything has ran smoothly until I upgraded my motherboard (yesterday).

Problem #1: I've tried hooking my surround sound up to my computer through the optical wire (the square one in case I'm making no sense) but for some reason sound only plays through two speakers. I changed the settings on my computer to 6 speakers, which is what I have. Everything is hooked up correctly. Any ideas?

Problem #2: I installed LimeWire on my computer. It installed fine but when I try to open it, after it gets done with the loading screen, it goes to a dark blue screen saying there was an error. I wish I could get it word for word but it said something like: "A program tried writing onto read-only memory" and also it mentioned: "ati2mtag" and it stays there until I turn off my computer. That screen came up 3 times and now everytime I try to open LimeWire my computer just shuts off. I'm lost.