I've been trying to use the Map to KML tool and it crashes every time. It also appears to leave a temp directory in the folder where I'm trying to export to each time.
Parameters I'm setting: Clamped features to ground (checked), Return single composite image (checked), setting an extent to a layer in the map project.
I managed to resolve the issue. It's a large map project with many layers. Examined the projection of each layer and found about three different projections in use so did some re-projecting of data to ensure everything was consistent. Also found one layer turned on, buried in a grouping, that was disconnected from its data source so fixed that too.
Well, turns out what I thought the resolution to this problem was didn't correct it. It did allow me to produce one map, but then all subsequent ones failed. I'm thinking now the map project has to be saved before each run, especially if any data has been added or changed. It appears I've got the tool running consistently now...fingers crossed.