Hi, Upon running g_helix_d -s md.tpr -n md.ndx -f md.trr I got the following output: Fatal error: rnr==0. Please tell me how can I proceed? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://maillist.sys.kth.se/pipermail/gromacs.org_gmx-users/attachments/20110625/0dbe612c/attachment.html>