Spider Monkey and jsdiDebuggerService Crash?

I developed GUI script debugger which runs on eclipse. (with xul runner 
and debugger service)

And my co-worker developed firefox plugin with c++.

when that plugin calls a script function through spider monkey on 
debugging browser(which is based on customized xul runner), whole 
eclipse crashed(JVM termination)

That plugin works okay in firefox. but it seems to crash with firebug 
too. so I think debugger service and spider monkey compatibility might 
be one factor of problem.

any idea?