What does the appearance of a crow/raven mean?

On my lunch hour the other day, a crow appeared at the top of a trailer near our building and instantly gained my attention due to his loud obnoxious squawking. After getting my attention he started to fly away and quickly landed upon my car. he was squawking and flapping his feathers and appeared to be trying to get in my car window that was open about 2 inches. I have never seen a crow in Michigan, although i know they probably live here. A co worker I was with told me the crow is a sign of Death, and to be truthful i have been a little freaked out since. Please tell me there is another myth or reason for this behavior.