I used to have the program crash with material editor constantly. Once I uninstalled the Wacom Tablet drivers it has been running smooth. If you use a tablet on your computer that may be the source of the problem.
Thanks MichaelPennyMP1, but we don't have tablets and we have disabled the drivers of the Wacom anyway. 5 computers working in a local network, same software, fresh I can honestly say we have tried everything!