In http://cran.r-project.org/bin/windows/base/CHANGES.rw2010dev there is a reference to the setting of a HOME environment variable on Windows: "R CMD / Rcmd now set HOME if unset, e.g. for use in Rcmd check." Was this intended to be R_HOME? Also, I don't understand the comment. Could someone clarify it. What is the use in Rcmd check referring to? Finally, just in case it really does mean HOME, I have had problems in the past with multiple software systems (R was not one of them) all using HOME differently and conflicting with each other so if this is a new use of HOME I would recommend that it be changed to a name that is not likely to conflict with other pieces of software.