Ah, this makes more sense. Yes, I see what’s happening now: something in your graphics driver is fubar and is generating these error messages at startup, but due to a bug in Panda when the code is compiled with full optimizations enabled, these startup error messages are not detected immediately, but are instead detected when the next texture is loaded (and it is then misunderstood to indicate a failure to load the texture).
I can fix that bug, so that in the future this will work correctly for you. However, there really is something wrong with your graphics driver, which you might consider attempting to fix by downloading a new graphics driver from your graphics card manufacturer.
David