Since mozilla 094 build, the java install script no longer puts the default JRE into plugins dir as the previous builds. So after users downloaded JRE from web, but they still could not load applets (since JRE was not in plugins).
This problem has been generated a lot of noise (i.e., "Sun JRE no longer works with recent mozilla", etc.). Netscape is actively working on getting help from Sun to fix the problem. The problem (bugzilla bug 100393) is currently a p1 blocker for mozilla/netscape. Even though there is a work around (user copys the default JRE file to plugins dir after downloading JRE), this issue needs to be resolved ASAP. That is why I make this a higher priority bug (p2, s2).