Assume this setup:

Green planes are chunk borders, red lines are the touching corners of four chunks

• A reactor on a single chunk, touching a border with coolant ports (I and O) on that side
• A turbine on a second chunk, touching the reactor on a border with fluid ports (O and I)
• Some kind of wiring or machine on a third chunk, connected to the turbine on a border

I didn't have much time to reproduce it all, but depending on how some of the chunks are loaded/unloaded before and after another, things that can happen include:

• The reactor's coolant ports stop transferring steam/accepting water until you break the multiblock and reassemble it
• The turbine completely resets (turns off, max flow set to 2000)
• Power output from the turbine stops until you replace the wiring or machine touching the power port

To reproduce use ChickenChunk's /chunkloaders command to see loaded chunks and either back away slowly until the reactor/turbine chunks get unloaded one by one, or add a spot loader to one of the chunks and teleport away

I've added a bit of code in 0.3.2A that should help a little with this, but it's difficult to reproduce 100%. Chunks, in general, are very finicky beasts. When in doubt, try not to have these sorts of connections immediately on chunk boundaries. The multiblocks themselves can span chunk boundaries quite easily.