i've had P3D for around 6 months now and I have never encountered any problems. But from yesterday I started P3D but it then came up with the loading screen but then immediately closed down but still saying it was running. HELP!

Same here. It started today. I get the startup window but then it crashes. I have had P3D for 3 months and have reinstalled it twice and it looks like I may have to

reinstall it again. I have searched tried many things from changing this to deleting that and nothing. Sometimes I don't know if it's worth the hassle.

Most of the time, this is caused by a bad entry or module in the dll.xml.  Move the dll.xml to a temporary folder and see if this fixes the problem.  The dll.xml is in the same folder as your p3d.cfg.  If P3D starts up okay after moving the dll.xml, then you can try disabling each entry one by one to see which one is the culprit (see page 2, AVSIM CTD Guide)(link in my signature). 

 

Best regards,

I had the same issue. I had changed my default flight. P3D would initialize, then disappear; but stay active. I reverted back to the original default flight (military jet at air force base) and all was well. If Jim's excellent suggestion doesn't nail it down, you may wish to check it out.

This happen to me several times. The way i solve it was by going to the appdata/local/Lockheed martin/prepar3d v3 folder and deleting prepar3d_Default.fxml and Prepar3d_default.wx. Let prepar3d construct a new one.