If you're repairing a non-boot drive you might try to unplug it before starting your computer (not while it runs). My computer run a repair on a particular drive everytime I restarted. Then I unplugged it, started the computer without the drive, turned it off again, plugged the drive back in and started the computer. It booted normaly. Is there any message about why it does that (maybe your drive is really faulty)? Also, if it is your boot-drive I can not help you, as you obviously can not unplug that.