This was a new project with the Q series, so i was checking the config and mainly the clocking possibilities, so the code only had #include <xc.h> and was just a few lines getting the reference clock to output on PORTE ( Should have but failed ).. Originally there was no plib directory under the v2.40/pic/include/ directory. the v2.40/pic/lib directory has or HAD 100s of PIC device .h and .inc files , and as xc.h was eventually looking for v2.40/pic/include/plib directory , I gave it one ...so yes my code did need a pic18f57q43.inc (.h) within a plib directory. Should say i have since found out I'm not the only person who hit this bug..