https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61628
--- Comment #6 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> --- I went to gfortran binaries and grabbed the mingw installer and installed it on my Win7 side. Compile the program, Un compressed the data file and ran it. C:\Users\jerry\prs\pr61628>gfortran pr61628.f90 C:\Users\jerry\prs\pr61628>a 681 469 319389 It appears to work fine. This is with the gfortran 4.10 verrsion as of today. Maybe try removing gfortran and re-install with todays.