For a week or so I've had a constant grinding noise coming from my MBP. It's centered on the left side of the laptop and it sounds to me like the fan is having issues. I took it to the genius bar today and they opened it up and cleaned it out (there was some dust), and said they couldn't see anything wrong with it. They offered to keep it overnight for observation but we all seemed to think that cleaning it out would be enough. But there must be something wrong, because now that I'm using it, it's still making the noise. Did I get an incompetent tech? Is the noise just normal? Could this be something besides the fan? He ran a basic hardware diagnostic and everything came up green, but something could still be up, right? I'd rather not part with it to send it in for repair, but the noise is driving me insane and anything is better than hearing it for one more week. Does anyone have any ideas for possible fixes that wouldn't involve being away from it? I have an early 2011 MBP.