Strangest problem... My little time-step symbol is solid red and it will often show 0 sec/sec (It's set to 15 min/sec), but the simulation is still running. I still see planets and moons moving around. To add to the confusion, as soon as I start recording a video, it jumps up to right around 15 min/sec and the symbol changes back to gray. I stop the recording, it drops right back down. The speed of the orbiting moons don't change.