Disk label problem

[Jurif]

Hi!

Few days ago some annoying things happened. At first I had FreeBSD 7  box
with one disk(SATA). When i added another dish (SATA)  my  box stuck when
booting up.

Somethink like this comes up:
Mountroot>

And i need manualy mount disk because disk label has beed changed and then
edit fstab file.

Now i'd like to know if is possible to "lock" existing hard disk label to
prevent this in the future if i add another harddrive ?

Best Regards,