Yeh its the one nano resistors that screw around with the program I think its because it makes the derivative numbers too big in the physics model per frame.
I was only mucking around posting this, But I had alot of fun making things just today and yesterday, I never really used in much before (Falstad), just touched on it briefly, went back this time a bit more full on, and I worked out I like it alot! and its very realistic, its very similar to just chucking wires together but alot quicker and easier.
I worked out tonnes of new strategy little odds and ends, cant really get what I want to work, but I work out little bits instead.
Its so easy to miss things, its good to sim your ideas around a bit just so you can get ahold of all the bits and pieces and angles ur missing, Im off to the electronics shop tomorrow probably get bags of components then off I go again.