Ok, Guys !!!
Good news :P So I took my Pc to apply my warranty, and they checked it all... Or so they say... I know they check all the components that I didn't buy there.
The cause of this problems wasn't the Hard Drive Disc, the Processor or the DVR-RW they said... And that problably was the Mother Board.
So they change my MB for a new one, and return the Pc to me with NO Operating System -_- !!! I hate them... Because it was a illegal copy of Windows XP, and it wasn't.
Anyway, I reinstall XP and it everything was fine
And then... On next reboot... The problem was there again !!! ._.
After that... My brother took my old pc and bought a new HD, because he needed the Pc and it was fine except that I have it's original PATA or IDE HD.
He buys a SATA disk so he can't connect it to that old Mother Board... So we chance Hard Drives and install XP on both and now both compurers are fine !!!
I guess it was a compatibility issue or an error with the port on my MB, beacuse the old HD works fine on the old Pc, and now that the old HD is away from the new Pc so is the problem.
Well, I posted this so I don't leave you guys hanging and I hope this help othe ppl with this rare issue.
Thax to all that replyed, U were of great help.