Steps to reproduce:
1) launch the following app
http://rehte.cn.oracle.com:8080/wshost/new_framework/new_framework/tests/javaws/manual/CustomProgress/jnlp/custom_progress_splash.jnlp
2) click Run on security dialog
3) close the app, don't clean cache, and relaunch again, if progress window shows again, bug is reproduced.
if the progress class is defined in an ext, like following app, the progress window will not show when relaunching.
http://rehte.cn.oracle.com:8080/wshost/new_framework/new_framework/tests/javaws/manual/CustomProgress/jnlp/custom_progress_pclass_extn.jnlp

Source code location:
http://rehte.cn.oracle.com:8080/wshost/new_framework/new_framework/tests/javaws/manual/CustomProgress/src/