Paul and Stefan, thanks for your fast replies. Heres the info you asked for :) release: Red Hat Enterprise Linux AS release 4 (Nahant Update 4) kernel: 2.6.9-42.9hp compiler: pgf90 7.1-1 64-bit target on x86-64 Linux -tp k8-64e launch command: mpirun -machinefile machines -np $2 ./nek5000 >logfile & Best, nab