Hi, Alaina Before you install GMX4.5.5, did you install cmake-2.8.8 and fftw-3.3.2 ? maggin -- View this message in context: http://gromacs.5086.x6.nabble.com/Gromacs-4-5-5-tp5009198p5009203.html Sent from the GROMACS Users Forum mailing list archive at Nabble.com.