[KenWittlief]

I dont know if this helps, but I searched the default code and drive_mode is not in the map file - so if its in your code you must have added it

the obvious thing to do is comment it out where you know it is (where you want it to be) and see if it compiles

if it does then search the .lst file and see where the other one is or check the map file and see if its in there - if its in the map file then its getting declared somewhere

could it be in the file with all the constants? did you declare it as a constant once and foget?