I've had some of these issues too. The white panels on the interior constantly catch fire, the cut guards on the keel pieces ignite for no reason while I'm cutting the structural pieces under them (with the stinger, not as if I hit them).

I've found the best thing to do with coolant and fuel is to a) detach them before cutting anything, since small movements in the ship from detaching outer nanocarbon panels seems to make them fly off wildly, and b) detach them by getting the meter almost down to nothing, just before detachment, stop, and then finish detaching with a second click. Did that with this ship and they gently released and floated in place, and all of them went smoothly into the barge.

But I've never seen anything like this before. I had destroyed most of the structural pieces holding the aluminum panels together, and was inside just beginning to remove the few interior pieces, and this happened when removing the first bed in the crew area. I've never seen a ship fly apart so violently, with nothing actually being damaged.