For some reason my SDK session just crashed. Three files were open at the time mb_init_test.c, mb_init.c and mb_init.h. Two of these files are fine, but the most critical file mb_init.c now appears to be empty and Win7 reports its sizxe to be 0kB.
Opening the file in any other viewer shows it to be empty. Its not too big so could re-write it, more I'd rather get it back. Just before the crash it finished an auto build so I do have the .o and debug .d files.