Intermittent trouble starting

2002 Jeep Wrangler. Starts great when cold. After running to the store and warming up, it sometimes has trouble starting again. I mean, you turn the key and you don't get a peep. Then after waiting awhile (and cussing considerably) it starts up okay. Any ideas?

check your battery cables, however mine used to do this and it ended up that the computer went.

Are you getting power anywhere else when this happens? Have you ever changed the battery?