I had this problem with a 20GB hard drive that came with my 360. It slowed the console down and made it take several minutes to boot the dashboard. When it finally did boot it showed how much free space was left but when I checked it, it showed no games what so ever. What I had to do to fix my hard drive is hook it up to a laptop, format it. Tried it afterwards and the hard drive still acted the same, it acted like it was never formatted from it's original format. So I had to put it back in the laptop, format again, then I filled the hard drive with random files until the hard drive couldn't hold any more memory. Afterwards, I again formatted the drive and put it in the 360. The 360 said "Unformatted Drive" so I formatted it on my 360 and then it worked perfectly fine.