I've had an 800 for a couple months now and it's always worked perfectly, then over the weekend I moved across town, and my last two rides, the elevation profile has looked like this:

http://connect.garmin.com/activity/229099738

http://connect.garmin.com/activity/229428263

For reference, the first ride has about 500-1000 feet of climbing and the 2nd ride probably actually has about 1500-2000 feet of climbing. I don't understand what's going on here. Can anyone help?