Random Short Lockups

I've surfed the forums but none of the problems seemed to hit on exactaly what i have.1st problem is that startup and shutdown each take about half and hour to go through (if at all).2nd Is the most reliable method of making the problem happen....loading a new webpage (like one I have never been to) this is when the computer seems to freeze, but not all the way, I still have perfect control of the mouse, and the clicks still go through but only after it seems to catch itself....And other times it doesnt take any provication to make it do this.3rd If this counts is that whenever it does this lockup thing, a small noise comes from the computer, like almost a beep, but not from any speakers, cant really explain it (its not from the case speaker either) Remindes me of a hard drive noise....kinda, but not normal HD.