Bright light zipped straight down, then stood still at about 10 feet off of the ground

I was traveling south on I-5 at about 6:00 PM on a Sunday evening in the fall of 1977. It was still daylight, and I was on the northern outskirts of Salem, Oregon. At that time this area was farmers' fields and small forested areas. The traffic was light.

As I drove, a bright light appeared in the sky to the southeast at about 1000 ft high. It zipped straight down, then stood still at about 10 feet off of the ground to the left side of the northbound lanes.
As I came parallel to it in my south bound lane, it zipped in front of my car remaining at the ten foot height off the ground, and about 50 feet in front of my car. It was about 2 feet in size and remained there for about 5 seconds.

It then zipped off to the right and came up behind my car staying at the 10 foot height about 30 feet behind. Again, it stayed for about five seconds. Then it zipped south again about 50 feet in front of my car.
After about 5 more seconds of hovering, it took off at a 45 degree angle into the sky. I have never seen anything move as fast as this light or remain so still when not moving. I have traveled that stretch of highway a lot. Usually all I see are red-tailed hawks.

source: http://ufos.about.com