I just performed a new install of Fedora Core 3, I was running Redhat 9 before. Is it just me, or does the compiler have major issues? This computer is a Dell-5150 notebook with a Pentium 4. All my scientific (heavy numeric computation) libraries are hitting serious infinite-loop bugs when I compile with optimization. This includes, but is not limited to: LAPACK Numeric Python (22.0) Numarry (Python) 1.1.1 CCP4-5.0.2 What's going on here?!? I re-compiled with GCC3.3, and it all works, but there must be tons of libraries effected by this. It can't just be my machine. Can anyone give me some insight on this problem? It looks as though this may be a known bug in GCC 3.4.2 which was fixed in GCC 3.4.3 (see: optimization bug in case statement). Regards, Jay Painter