Hi All Just a warning to other people who might be about to update and I am not sure how to guard against this sort of problem. How are bioconductor and CRAN coordinated? I updated my version of XML (from CRAN) and had some problems using biomaRt. On issuing library(bioMart) I got a message saying that iconv.dll could not be downloaded and reinstalling the application might fix the problem. Also shown were messages about unable to load XML or the biomaRt namespace. I re-installed XML from bioconductor and it all worked again. My sessionInfo() below is the version that is working, not the problem configuration. Regards John Seers > sessionInfo() R version 2.9.0 (2009-04-17) i386-pc-mingw32 locale: LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United Kingdom.1252;LC_MONETARY=English_United Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252 attached base packages: [1] stats graphics grDevices datasets utils methods base other attached packages: [1] biomaRt_2.0.0 RWinEdt_1.8-1 loaded via a namespace (and not attached): [1] RCurl_0.97-3 tools_2.9.0 XML_2.3-0 >