Source: http://cmrr.ucsd.edu/people/Hughes/HDDEraseReadMe.txt

Q: How can I bypass security freeze lock?

A: Three different ways can bypass a BIOS security freeze lock:
1. Most preferred method: If another computer is available, boot the drive
from another computer. Since the freeze lock is entirely BIOS dependent, another
computer's BIOS may not freeze lock the drive.

2. Second method: Switch the drive to another drive channel or another position
on the channel, e.g. Switch drive from secondary master S0 to secondary slave S1
or vice versa. Some BIOSs do not send the Freeze Lock command to all channel
master/slave positions.

3. Least preferred method: **There exists some danger to your drive in using
this method, use at your own risk** Shut down the computer system. Unplug the
four-wire power cable of the hard drive while leaving the signal cable plugged in.
To eliminate the danger of ESD, always ground yourself when removing the power
cord. Power on the system and boot into DOS with a DOS boot disk. Once DOS has
booted up and you are at a command line interface plug the power cord of the hard
drive back in. Run HDDerase.exe. The logic in this method is to prevent the
drives detection in BIOS, which is when the freeze lock command is issued.