I just purchased my first car GPS unit (had a few handhelds). It's a Magellan. Every time I power it up (start the car and power it from the lighter plug) a screen comes up warning me about driving and looking at the unit or something else. I've never even taken the time to read the entire warning! But it has an "Okay" button you have to push... unless I wait. I automatically clears itself after about 15 seconds or so.
I understand how annoying your "Agree" thing is. Mine just says "Okay" instead!