I know this is quite a handwaving, stupid question, but I don't know where else to ask it and maybe somebody here can at least point me into the right direction, because I'm stuck. I have a program package that were using here (OpenFOAM for those who know it). My problem is that when I compile and link this package on CentOS 5, it won't run on CentOS 4.x-machines but stops with a floating-point-exception. The funny thing is that my experiments with strace and gdb indicate that the problems occur during the loading of an .so (that does not belong to the package). I was able to remove that so from the build, the program then failed with similar symptoms at another library. Has anyone here seen similar behaviour and what would be a possible solution? (to compile under 5 in such a way that it runs on 4) My problem is, that moving all machines to CentOS 5 is not possible, because our cluster-solution (Rocks) is based on 4. Any hints (how trivial they may appear to you) are most welcome.