Try running with the following JVM property:
-XX:-OmitStackTraceInFastThrow
From the Release Notes:
The compiler in the server VM now
provides correct stack backtraces for
all “cold” built-in exceptions. For
performance purposes, when such an
exception is thrown a few times, the
method may be recompiled. After
recompilation, the compiler may choose
a faster tactic using preallocated
exceptions that do not provide a stack
trace. To disable completely the use
of preallocated exceptions, use this
new flag:
-XX:-OmitStackTraceInFastThrow.