jQuery 1.7 is *still* returning the event.layerX and event.layerY error in Chrome
Worked it out - it wasn't immediately obvious either, but posting this here for anyone who gets tripped up by this in future:
It was a Chrome Extension that used an old version of jQuery causing the issue. Disabling all Extensions and re-enabling one at a time helped me find the perpetrator. Hope this helps for anyone else with this issue in the future!