Can anyone explain why deleting shaders will fix crashing issues with P3D? This morning I was unable to launch a flight in the Nxgen Cj4x. P3D would CTD just before the scenery loading process completed. After deleting the shaders I was able to successfully start a flight. OTOH, I’ve been unable to start a flight in the Lionheart Creations Zenith, despite deleting the shaders multiple times, even though it appears to crash at approximately the same point in the loading process?

I have a lot of add-ones installed, e.g, GSX, SODE, add-on scenery, add-on aircraft, ASP3D, ASCA Chaseplane etc, so I suppose the likelihood of instability increases with the complexity of the install, but sometimes it seems like even the simplest things are fraught with difficulty. 
 

 

The shaders are compiled using code specific to a P3D version and also for the video card and driver in use.  Changing any of those may leave you with compiled shaders that are in some way incompatible.  Deleting the compiled shaders forces the sim to recompile the shader code in the current environment.  And it should be noted that sometimes Windows updates install new video drivers, perhaps without you realizing it.  That can cause your shaders created using the previous driver to be wonky or downright dysfunctional.

That said, it looks to me like you're more likely to have a scenery issue than a shader problem.  Deleting the shaders may or may not have been causal in getting it to run that one time.  If your default flight is something other than a default P3D acft on a default P3D airfield, you'll want to reset it back to that.