Your best bet especially if NO information is on the laptop is to completely wipe it out. They should have given you a restore disc or told you how to go about doing it especially if it's from Compaq. If you can boot into laptop there is usually a place in all programs where you can create a system restore disc that would wipe out everything on Hard drive including their security protection program.
like someone stated above, press F8 key and see if it would allow you into the system.
Another thing you can try is to download something like Ubuntu, free open source OS and download live CD and boot it up. If that message comes up again, then check your BIOS or setup, usually F2 key and look closely for something weird about password lock or something. If not, then there may be something physically added to laptop to prevent it from booting up.