Well, being so new to this and having only found 2 caches so far, my first attempt was a good old fashioned n00b hazing. My son and I were looking for our first find in an off-leash dog area in a huge urban forest. I entered the coordinates and hints with painstaking diligence and we set off to find our treasure.
I entered the info inside the house with no satellite lock and didn't think much about it. Knowing the general area I did not turn on my GPSr until we were within a couple hundred meters of the location. I then found to my horror that the GPSr reported the location as being some 65km east of us!
Not deterred I rebooted it and low and behold it was now 3 km to the west of us! Getting closer.
Well after tossing around several theories, all of which blamed Magellan directly, we tried to find the cache without GPSr.
To make a long story short, we got questioned by muggles, made a keen spectacle of ourselves stomping around a clump of trees and to make matters worse we both stepped in dog doo.
I later discovered that I had used the wrong datum on my GPSr and the poor thing had no idea what I was on about.
I have it figured out now and happy to report I am much more discreet and no longer look for treasure in doggy doo minefields.
Definitely a D'Oh moment.
Glad to have that one out of the way
Edit: We never did find that cache!