Lost Prop Plane Capability?

Hello y'all,I have been flying the Citation X and occasionally the ATR 72-500 turboprop lately, nothing else. Last evening I decided to go for a putt in my AFG King Air 300 and when I tried to start it it would not start. I then tried in the default King Air 350 and the same happened. Restarting FSX and rebooting the computer did nothing to help.So I tried the default Cessna Skylane and the same thing happened - turns over but will not start. I then hopped in the ATR, cranked it up then switched planes to the default 350 and it came up running but both engines then quit. So I know it's something about fuel but I haven't a clue what it could be. Another thing I've noticed lately is the some gauges, engine and airspeed gauges in particular, in all planes I fly jump around and sometimes the planes (on autopilot) take sudden turns off course before correcting again. Any thoughts? Dolph