The Java error when attempting to use the stemmers in the Snowball or tm packages on Windows machines is caused by Quicktime. See prior posts in this thread. The workaround is to uninstall Quicktime. After much trial and error on machines spanning WinXP/2k/Vista/7, I finally verified this as follows: 1) Fresh installation of Windows/Java/R. Snowball package works perfectly. 2) Install Quicktime. Java errors produced when attempting to use Snowball package. 3) Uninstall Quicktime. Snowball package works perfectly again. Many thanks to profs Ligges, Hornik, and Feinerer for their kind help in diagnosing this.