Linux Netscape 6 (Sun Java 1.3.0_01) freezes when an applet tries to load a class in a method called from JavaScript. The browser does not freeze if the applet classes are local files, it only freezes if the applet is on a web server (http). Press the Load button to try it.

Ns6JsCLF.java
Zzz.java


Related bug: Netscape 6 + JavaScript AccessControlException at file loading