Why does this happen so often on the left coast?

When I first got my Garmin I took it on a drive where I knew I was going, when I got off the interstate and started to turn left it insisted I turn right, which would of had me driving thru a guard rail, down a hill and into some farmers corn field. When I insisted on going the only way possible to get where I was going at every little road and driveway the Garmin recalculated and insisted I turn around, it wanted me in that corn field bad. Ever since then I went back to using paper maps. This happened in the middle of the country not on the left or right coast.