Setup I had was power from Immersive Engineering diesel generator to Draconic Evolution energy storage multiblock, output flux plug of that multiblock was the particular item that I interfered at the time of crash.

http://paste.feed-the-beast.com/view/3c267bc5

Could not reproduce the crash, steps were something like this:

1. mash flux plug's max transfer amount field full of 9's
2. change name to random name
3. change ignore limit from false to true
4. press enter and close the GUI
5. wait few secs for update (does something funky with max transfer value) see that number was negative, few "MC not respondings" from Windows after that game crashed.

Version fluxnetworks-1.12.2-3.0.1

Couldn't recreate.