Hi! Pinned the problem with plot down a bit. I can reproduce it with only 2 lines of R on my Windows XP machine. (today reinstalled R1.9.0) and Bioconductor packages updated. Can anyone reproduce this behaviour? (I am surely reproducing this error only if library(ROC) is loaded at the beginning of the session.) z:\devel\Paper2004\patrick3>Rterm R : Copyright 2004, The R Foundation for Statistical Computing Version 1.9.0 (2004-04-12), ISBN 3-900051-00-3 R is free software and comes with ABSOLUTELY NO WARRANTY. You are welcome to redistribute it under certain conditions. Type 'license()' or 'licence()' for distribution details. R is a collaborative project with many contributors. Type 'contributors()' for more information and 'citation()' on how to cite R in publications. Type 'demo()' for some demos, 'help()' for on-line help, or 'help.start()' for a HTML browser interface to help. Type 'q()' to quit R. > ls() character(0) > library(ROC) > plot(hist(1:10,plot=F)) Error in xy.coords(x, y, xlabel, ylabel, log) : x and y lengths differ I was trying to reproduce the error under Debion linux. There I do not get such an error. Eryk.