I was out of town training for a new job recently and went caching one day and my GPS worked fine. A couple of days later when I got ready to go caching it would not lock onto the satellites. I tried everything I could think of even out in a wide open parking lot but it would not get a lock. I tried again over the next several days and nothing. I even missed out on a couple of FTF's because it would not work. Well, I just got back home yesterday and the users guide that came with the unit was not any help so I decided I would do a little research online to see if I could figure out how to fix it without sending it to Garmin. I found a website with the info I needed to reset it. I would lose all of my waypoints (about 400 of them) in the process so I just transferred them from the gps into GSAK, did the reset, then resent them to the GPS. Now the thing works fine. I don't really know what was wrong with it but the reset fixed the problem. The website that I found is http://www.gpsinformation.org/dale/secret.htm#reset
It has a lot of info on the older models from Garmin but I thought this info may come in handy for some folks that use Garmin.