First off, I have an iphone 3GS which I recently jailbroke using the new spirit jailbreak. At the same time, I upgrade my Navigon SW to the latest 1.5.1 (paid software, not cracked). Since then, my navigon has been dropping GPS signal and generally acting flakey which it never did. Navigon was always solid from the beginning but this latest build has been acting strange. I've read some posts that other users are experiencing the same thing. The strange thing is that I did load Tomtom's GPS SW and it also would drop signal every once in a while. Could it be the jailbreak? The 3.1.3 update? Navigon 1.5.1? Any thoughts?