Error "avr-g++: error: CreateProcess: No such file or directory" When Compiling Script
Turns out that McAfee's Host Intrusion Prevention had decided to start blocking avr-g++.exe. Not sure why it did so all of a sudden, but it's an easy fix once you know where to look. Anyone finding this in the future should be sure to check their antivirus logs to see if the compiler's executable is being blocked.