I found some references to it when wikiaing/googling about, but no solutions.

Appears to be an erroneous error as I get it whether or not EXE4J_JAVA_HOME and/or the typical Java environment variables are filled out.  I'm able to run spark fine from the command line (via startup.jar) though.

Platform is Vista x64 w/Sun JDK 1.6.0_07.