I found the problem - I was running the 1.4.2 rrdtool package for Solaris i86, and it doesn't draw graphs properly: http://www.opencsw.org/mantis/view.php?id=4361 ... and, as it says there, I downgraded rrdtool, reinstalled Perl and RRD::Simple - and away it went. Thanks to everyone for their help and support. -dan