Adjusting and blocking files? You lost me there...
If you copy the /profiles directory to your computer first you could try to reset the unit to default values. Next, see if you can load a close by cache and see if it shows on the map.
BTW, have you checked zoom levels in setup > map > advanced setup > zoomlevels > geocaches Use anything above 1Km/mile, srcoll the map to the cache location and start zooming in.
I should of said adjusting the filters. Just went through the setup>map> etc, etc no luck there either.