ArcMap crash on "Share as Tile Package"

Hello,

I am trying to create a tile package (.tpk) with ArcMap. It hangs for about 10 minutes on "preparing to generate tiles", and task manager shows ArcMap as Not Responding. And then it moves onto "Generating tiles for level 0 of 18", and crashes almost immediately.

This seems to happen every time I try to make the map.

I have made Tile Packages before with no issue. Has anybody seen this before? What could the problem be?

I am using ArcMap 10.1

Thanks
Michael