Hi I get a segmentation fault with the following: library(affy) test<-NULL normalize.quantiles(test) This should return an error (admittedly I was being a dumb user). Package: affy Version: 1.1.7 And platform i686-pc-linux-gnu arch i686 os linux-gnu system i686, linux-gnu status major 1 minor 6.2 year 2003 month 01 day 10 language R