I really wonder what I'm doing wrong or if it's a bug of FS2004:Whenever I shut down a plane's engine(s) (with throttle cut off) and turn off all the switches I either get an electrical failure (all avionics dead) or I can't switch the engines back on (all avionics work but the enignes just won't start, no matter what the thottle or mixture setting). Am I shorting something out by using a wrong sequence? I'd go for a bug, because I can't get rid of these failures via the failure menu. Only when I reload the aircraft does everthing work again.

what is the aircraft(s)? I am assuming you have brought the mixture back out of idle cutoff and have the battery on, etc. Also, in RW one shuts off avionics before engine shutdown to prevent surge. FS doesn't care of course, technically.

I had it happen with the stock Beechcraft Baron 58 and also with the C-119 Flying Boxcar Daisuke Yamamoto that I'm currently using.

Your battery could be running flat. How long is the aircraft shut down before you try to re-start?

Not long. Maybe a couple of minutes. I want to shut the aircraft down when I'm going to save the flight and continue it another day. So, I usually shut down, save, load and try to start the engines up again.But I'm gonna try switching the batteries off before I shut down the engines. Maybe it was a surge.