I have an RCA 650 watt Surround Sound system, and for the past few months, every time I turn on my receiver, it makes a grinding noise. It usually stops after a few minutes, but it has me worried. I have had it for about two and a half years. I know this is not near top of the line, but it works great and the sound effects and such are crystal clear, but I do not know if this is the start of a major problem. Any advice? Thanks for any information you can give me.