Receivers and Audio Components

I bought a Companion 20 from Amazon, and the shipping route is very long. When it arrived I immediately set it up and found that if I turn the volume up, there's a "Shh" sound. The worst part is: After about a week of normal use, if I accidentally moved the main speaker for a bit (Now even if I don't move, it still happens randomly), then the left speaker went off and on and off, and finally off. Then I had to unplug it and plug it in again for it to work. So now I can't touch the speaker otherwise the left speaker will go off. One thing I'm sure, the cable is connected firmly.

How do you replace fuse?And can I perchase online? or other?

when used with the DenonDCM-260 stereo cd player the speakers work, had to move the system I hooked up the wires wrong, then smoke came from the back. When the stereo is on it just hums.

I had a new video card installed, an AMD Radeon with two out puts so I can keep the DVI hook up to pc and hdmi hook up to tv but now all audio is going to tv no matter what I am doing on pc. Even if I choose a different input on tv there is no audio on pc neither from speakers nor from headphones.  And this is not only with playing a video/movie but even if I want to play a game the audio is going to tv and also if I want to use the phone service from gmail or voice chatting it is the same problem.