Trouble getting engine to turn over sometimes...

So i'm not really sure why my Jeep does this but sometimes i'll go out to start my jeep and it won't turn over. So I mess with the shifter just putting it in park and neutral (One of my friends told me to try it) and sooner or later it turns over and starts up. Anyone know whats wrong with this thing and how to fix it?
Thanks for reading!

Neutral Safety Switch....?

http://www.naxja.org/forum/showthread.php?t=930779&highlight=Neutral+safety

should get you "started"-- pun intended

--Shorty