This was tracked down to a optimizer/JDK problem (if ran with -Xint it was OK). Upgrading to latest patch level solved it (no need to run with -Xint). http://publib.boulder.ibm.com/infocenter/javasdk/v6r0/index.jsp?topic=%2Fcom.ibm.java.doc.diagnostics.60%2Fdiag%2Fappendixes%2Fcmdline%2Fxint.html
This was tracked down to a optimizer/JDK problem (if ran with -Xint it was OK).
Upgrading to latest patch level solved it (no need to run with -Xint).
http://publib.boulder.ibm.com/infocenter/javasdk/v6r0/index.jsp?topic=%2Fcom.ibm.java.doc.diagnostics.60%2Fdiag%2Fappendixes%2Fcmdline%2Fxint.html