anon156 if u hit f4 =turn it off before turning in the research = the max potions cheat you should be fine then you can reactivate f4 again if you like when your done credit goes to someone else not me for this
PS: allways be safe save your game first before trying things
It crashes because you have unlimited potion option enabled, most likely. That option also affects the crafting items and thus when you turn them in and game tries to remove them, the trainer tries to keep them and thus they don't come to an agreement and game crashes. Simply disable unlimited potions (F4), turn the stuff in and then re-enable it.
Many thanks.