Peculiar engine trouble

[Hotshot]

Now and again none of my aircraft will start, whether with CTRL+ E or panel starter: the props spin, but engines refuse to fire. This affects both default and imported aircraft. The only remedy is to relaunch fs9. Any clues?

Another peculiar fs9 problem:  without warning, an aircraft will suddenly stop flying, and go into a vertical dive. Sometimes I can pull it out by feeding in massive up trim, at other times there's a spectacular crash. Again, clues would be very welcome!

[Sovien]

Try deleting the last add-on you installed. See if that clears things up. I've not experienced this, but normally people start to see FS9 do weird things after they've installed a new add-on aircraft, scenery, etc.

[Ashar]

Try to delete your FS9.cfg...Beware that you will loose any tweaks that you had used in the cfg file as FS9 builds a new one at start up...