Hi, I have a program (attached) that is relatively simple, but numerically intensive. It computes the abundances of the chemical elements generated by big-bang nucleosynthesis. At the moment, the executable takes no command line arguments, it simply runs the standard model. When I build the program without profiling, it produces the right answer. When I build it with profiling (runhaskell configure --enable-executable-profiling) it runs without error, but gives completely incorrect numerical results. I'm using ghc 6.10.4 built from source using MacPorts. The program is mostly self contained, but uses the hmatrix package to solve a linear system. Note also that the "Vector" type is hmatrix's Data.Packed.Vector and not the one from the more familiar "vector" package. I was wondering whether this profiling problem is known. Best Wishes, Greg