Unable to compile IE permutations with JRockit (illegal arg "-logLevel")

SmartGWT version: Latest release (4.0)

Build Info: GWT Maven plugin (version 2.5.1) with Maven (m2e) launched within Eclipse Indigo and where Maven is executed using JRockit JDK 1.6.0_31.

The problem: Compilation for user-agent gecko_1.8 succeeds without issue. However, compilation of user-agents ie6, ie8, and ie9 all fail with the following error message:

[INFO] Process output
[INFO] [ERROR] Could not create the Java virtual machine.
[INFO] [ERROR] Unknown option or illegal argument: -logLevel.
[INFO] [ERROR] Please check for incorrect spelling or review documentation of startup options.
[INFO] [ERROR]

The issue is resolved by switching the JDK to the standard Oracle (Sun) JDK 1.6.0. Why do those specific user-agents require the additional passing of the –logLevel JVM argument? Also, how can this be easily disabled? We’d prefer to compile using JRockit.