Hi, The functions read.celfile and read.cdffile in the package affy are reading Affymetrix '.CEL' and '.CDF' files respectively. Trying to load corrupted files (i.e. with lines missing, or with aunt Annie's chocolate cake receipe inserted in the middle) will puzzle so much the parser that it will precipitate R in its fall (crash, segmentation fault). A more robust parser will come with the next version (and will be within few days in the 'development' version of the package). Regards, Laurent -------------------------------------------------------------- Laurent Gautier CBS, Building 208, DTU PhD. Student D-2800 Lyngby,Denmark tel: +45 45 25 24 85 http://www.cbs.dtu.dk/laurent