I had a funny problem with my java applet in web start application – it worked every second time I refreshed web page.

After a little debug I found out that java machine didn’t make it in time to shutdown, start and show applet.

Solution was rather fun:

<param name="separate_jvm" value="true" />

It helped because now new instance off applet launched in a new JVM, simultaneously with closing old instance of applet in old JVM.

But be careful if your applet writes something to user disk or etc – both old and new instance can be doing is for a little time!