A problem with Gromacs-3.3: When I try ty run grompp using a.gro and a.top files, system says that number of coordinates in a.gro, 440, does not match number of coordinates in a.top, 0. That's strange because the both files were converted by pdb2gmx from one: a.pdb. Maybe it's necessary to specify number of atoms somewhere in a.top file?