My ProMedia 2.1 system sometimes works fine. Other times when I power it up, it doesn't fully get there. In this case, the power indicator light doesn't come on and there is light crackling/noise that is not affected by the volume knob. Occasionally, the system overcomes its power up problem and finally kicks in, usually with a good low end pop. Again, this is not all the time, just occasionally. When it works, it works great. When it doesn't, it's pretty stubborn and won't power up until its ready. Thoughts?