My Mac Pro started having issues about 2 weeks ago. The screen would go blue every now and again for about 3 seconds and then go back to normal. It kept doing this off and on. Two days ago the Mac Pro started making a buzzing/humming sound, loud enough to hear in the other room. I shut it down and tried to fire it back up and it began making a clicking noise, then the humming came back. The screen froze at the grey screen and did not show the white loading wheel. I've swapped out the drives and still the same. The Mac is about 2.5 yrs old and I use it for video editing (FCP) and photo editing (Adobe CS3). I've never had any issues until now. Before I take it in for testing, any advice?!