I am using Big Reactors and Mekanism together and they seem to create Infinite power after the buffer is full even when the reactor is offline.

Screenshot: http://gyazo.com/0631044a2370465cad51de9befb66c8e

P.S. I am not using TE.

I need more info here. I need version numbers for Forge, Mekanism and BR. I also need a full description of your setup, and preferably also a screenshot of your controller's status UI showing the infinite power bug.

No new info in one week, closing. Please reopen this issue if you can produce the requested information.