I’m Danish and don’t speak or write Norwegian, but since the languages are so similar I think I can at least somewhat answer your question. In Danish forebygge=(try to) prevent something from happening by taking precautions against it: forebygge kriminalitet forebygge sygdom forhindre=prevent/stop something from happening: Det dårlige vejr forhindrede mig i at nå frem. The bad weather prevented me from arriving. It would make no sense to write ”Det dårlige vejr forebyggede mig i at nå frem.” because it would imply that the weather had deliberately prevented me from arriving by taking precautions.

Hee, æ vil lære norsk! vil du hjelp mæ? :)