it's hard without looking at the project in questions. The errors lead me to believe something isn't set up right with the GUIutilty.processEvent file. Looks like it's trying to get a file and can't find it. I'm not sure how your using the library tho
Whats the script that's trying to use it? And why? Also, try making a new project. Build and export, see if you get the same error, if so, try re installing unity. Slowly remove game objects from scene until error goes away. I'm not sure how else I can help at this stage.
