This sounds strange.... if you ever fix it let me know, I had a computer do this to me once, but it fixed itself after a week (that was an old 286, though).
Just out of curiosity, how do you format a drive with it not loading? Is there an option in the BIOS?
Is it at all possible that the power connection is loose but still semiconnected? And also if you need HD Tools, I check for Freeware Progs on CNET.com for utilities. Most of the time they will tell you the problems. They wont all fix them for free though as modern freeware is actually like a sampler to get you to unlock the remaining parts of the program
Could be a problem with device drivers, hardware or software. This problem can be solved by uninstalling new software, updating device drivers and making minor configuration changes . From Fix computer hanging, blue screen of death, troubleshooting
. You can also run a free registry scan using utilities from Registry cleaner software, utilities
Download a program called HDD Regenerator form this link http://www.shareup.com/HDD_Regenerator-d
Open your computer, take the hard drive out and plug it on another computer and scan it wiht HDD Regenerator. It will tell you what's wrong wiht your HDD, maybe fix it or cancel the damaged sectors and will let you to continue to use the non-damaged sectors on your drive, Good luck.