First, thanks for a great game.
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I've found that if I mouse over the item being produced in an assembler or chemical plant with 3 or more ingredients and simultaneously pressing escape or E the game most often hangs or more seldom crashes.
It happens regularly on the items I've tried: blue science packs, advanced circuits, batteries and explosives. Does NOT happen with sulfur and sulfuric acid.
I've attached Factorio and OS X crash logs and the savegame.
I'm running OS X 10.10 on a 27" 3.4 GHz i7 iMac with 16 GB ram with a Radeon 6970M 2 GB.
Dropbox link: https://www.dropbox.com/s/8h774zao98oa0 ... s.zip?dl=0
/Chris
Edit: It seems to have to do not with the ingredients but when the items produced are in the inventory.