I have a bug for you, When put a Lapotron crystal into a MFSU the Lapotron automatically losses all of its charge but doesn't charge the MFSU, I mean the energy that the lapotron had, will be lost.
Info:
Minecraft 1.4.5
Forge .408
IndustrialCraft (this version)
BuildCraft 3.2.1
Forestry 1.6.2.1