Folks, I need some advice. I'm very new to Mac. I received my refurb 21.5", 3.2 last week. I've had a couple of issues and I'm wondering if I should return it. I've had two occasions where I get stuck at the grey screen. I had to call support last night because the OSX disc wouldn't even help boot the machine. After the support call, the fan ran all night while the iMac was asleep. It was just the regular fan noise, but it usually turns off in sleep mode. Now I can't reboot if my printer USB is attached (the only USB). Thoughts (and thanks for any advice)?