If you are familiar with it and can provide some assistance please contact me off list (unless there is interest from "the list", that is... :) In short, the problem is: I compile optimizing and get a useless message (note -O2) usr01@host01:appx$ xlC_r -DAIX -O2 -qlanglvl=compat366 -I../../common -I../../sock/include -I../../omf2/include -I. -c -o ./output/appx.o appx.cpc 150 1500-010: (W) WARNING in KillHandlerThread(void *): Infinite loop. Program may not stop. 1500-016: (W) WARNING: Compiler problem occurred while compiling std::vector >::_Buy(size_type)@AF367_103: A file or directory in the path name does not exist.. 1500-034: (S) Cannot create object file. usr01@host01:appx$ I compile without the -O2 and get a different useless message usr01@host01:appx$ xlC_r -DAIX -qlanglvl=compat366 -I../../common -I../../sock/include -I../../omf2/include -I. -c -o ./output/appx.o appx.cpp 1500-016: (W) WARNING: Compiler problem occurred while compiling CThreadLoggerWrapper::__dftdt(): A file or directory in the path name does not exist.. 1500-034: (S) Cannot create object file. usr01@host01:appx$ Question is: What is the message telling me? Thanks everyone. Hopeless... ET