Yes, for many modern notebook, it has a new function so-called "drive-lock". To use password to lock the hd even the hd is swap to another notebook.
I also drive-lock my notebook hd, and glad to see your case is what i expect to see if one day my hd was stolen.
For un-lock the hd without passwd, I will suggest:
Take to a old desktop PC in will the BIOS does not support hd drive-lock to see whether it can pass it out.
Or use "Ultimate Boot CD" from http://www.ultimatebootcd.com/
to make a boot CD n use one of the program called "ATA Password Tool 1.1" to unlock any locked hd as claimed by this small program. I didnt ever try , for i dare not in case my data was all messed up.
Have a try n look for yr turn our feedback.