May be a bios problem
recently tried windows media center - which fired up by installing something which turned out to be on my ext sata drive.
now drive is write protected.
can't unlock it
will not accept any changes to security to drive - because it is write protected.
my login has administrator privilege
one suggestion has been to use partition program to reset write protection but not destroy data
it seems that the bios may have a glitch which may have locked it up