Nav System Issues on '05 Eddie Bauer

I just purchased an '05 Eddie Bauer about a week and a half ago. It came with the nav system, which I wouldn't have purchased if I had ordered the vehicle from scratch, but since the dealer stock vehicle had everything else I wanted at a lower price than I was willing to pay, what the heck.

Aside from it being fairly crude compared to other nav systems I've seen, it's a fun little toy and was dead on for the first week. About 4-days ago, however, it decided to stop knowing where the heck my truck is at any given time. Sometimes it can get within about a half a block from my actual location, but mostly it's about 5 to 10 blocks off. Does anyone have any idea what could be causing this issue? Is there a way to "reset" the system so it clears out whatever gremlin has attached itself to my dashboard device?

Any help is greatly appreciated.

relax...

it's a government conspiracy...

from time to time, the government scrambles all the locator signals in use... suppossed to combat against enemy missle attack, but get a 10 mega-ton nuke within a couple miles of it's intended target, it's toast.