I use an iomega prestige 500GB Desktop External Hard Drive. I've had it for half a year now and has been working great. But suddenly after I completed a copy of 200GB from the hard drive, and formatting it, the computer doesn't recognize it in disk utility or finder. Also, the light is very dim even though its plugged in and all. (OS X does recognize when you pull out the chord without ejecting it.) So how do I get my imac to recognize it? anybody?