If everything else fails and you are willing to lose everything in your hard drive. THere is a solution. Go to http://www.hgst.com/hdd/support/download.htm and download the Fitness Tools. Use that ISO file to burn a CD, which is bootable automatically. Then you can use a tool called erase disk in side to erase everything in your hard drive. Including the Hidden Partition.
WARNING: IT WILL ERASE EVERYTHING EVERYTHING!!!
After that you will need to reinstall OS and all the drivers, there are numerous clean install guides out on the net.