It is probably the BIOS password it is asking for. I take it that it is not preventing you from booting up? It is just a "nuisance" that you want to get rid of?
Have you tried getting into the BIOS ? To access the BIOS usually pressing f8 right away at start up with get you in there, but it could be a different key (mine is DEL) make sure you select it quickly. In BIOS look for the security tab or somewhere that says password. Usually you can turn off some passwords from there