Yo Karlos!
Here's the one, two three:
1-If a Mac will boot with the drive connected then...
Alsoft's Diskwarrior has a patented system of rebuilding the b-tree. Use it and you might be able to simply bring it back to life in it's present form
2-If the Mac will boot with the drive connected, but doesn't/will not mount, or you don't want to get Diskwarrior, or behaves very erratically on reads/write then Data Rescue.
(
http://www.prosofteng.com/)
This little number ($50 USD) has come through a couple of times for me and it's $40 cheaper than Diaskwarrior. It will not restore the drive in place, but you WILL recover "en mass." I was able to recover 90% of a 160GB drive than neither Apple's Disk first aid, nor Diskwarrior would repair. It is great.
3-If computer won't even boot and hardlocks the problem is hardware. Either the drive itself or one of the other components.
I've had this happen on a PC once. The computer wouldn't boot w/ the drive attached.
I also had a case where a sketchy firewire enclosure would cause the drive to mount sometimes and then not other times. This corrupted the b-tree, but with Data Rescue and a working firewire enclosure, I recovered almost everything, formatted the drive and it is still in service.
I have also dealt with various interface cards causeing system lockups w/ a certain drive (but perhaps not another).
So... A problem like you are haveing is NOT the OS, but must be hardware.
Let me know if you would like any specific help. I've worked on Macs since my days when an A2000 was my prefered choice.
