There I am, driving along the M25, when somebody in front of me decides to swerve across three lanes to make an exit. At first I was upset, but one peek through the back window and I could see it was somebody intently following a sat-nav.
I'm not saying that because the driver who cut me up was using a sat-nav that made it okay, but we've all been there. You're peacefully driving along when suddenly your sat-nav beeps out, "In 100 yards, turn left." Thanks, I'm doing 70mph, that's in about two seconds.
After some time with a sat-nav you get used to being commanded and take it in your stride, but when you first get one, you can't help feeling under its complete control. Particularly if you have no idea where you're going.
My only advice is to try, when possible, to have a look at your route on a map before leaving the house. Sat-navs are good, but you have to take them with a pinch of salt sometimes, and make sure you don't rely on them completely.