Minecart Activated T Flip Flop Crashes Game

I'm trying to create a T-Flip Flop to power my "Monster Masher" mob grinder, with a Minecart timer mechanism. The TFF I'm using is the Cauldron/Comparator model, and it works great, at least until I hook it up to the timer.

After that, with an empty cart, it either freezes and crashes immediately after touching the Detector rail, or takes several minutes. If a mob, such as Mr Sheep in the second screenshot, wanders into the cart, it will crash immediately the second it touches the Detector rail.

To Reproduce:

1. Build a Cauldron/Comparator TFF
2. Hook it up to a loop of rails and set a minecart in motion, with a Detector rail attached to the TFF
3. Laugh maniacally as your Monster Masher finally works
4. Game will crash after aforementioned delays