This computer is making a grinding noise; it sounds like it might be the fan. I have the cover off and it really sounds like the fan in the back is about to go out. Will it hurt the computer if I leave it on as long as it's turning? The computer is an HP Pavillion 6535, about 3 or 4 years old... Can it be fixed at home if I go buy a new fan, or is this a do-it-yourself project that blondes should avoid? I added some RAM to it a few months ago with no problem. And...