The current version (November 6, 2009) of the “/spark/build/installer/spark.aip.tmpl” file names the icon that is placed on the Desktop as “Spark.exe”. I believe that this should be simply “Spark”. This error occurs in the .aip file at (left nav) Project Definition > Files and Folders; (right pane) Desktop. Right-click on the name, select properties, and edit the name to “Spark”.
(I tried entering this as a bug in JIRA, but could not find the Create Issue link; are community members not allowed to directly create issues?)