What kind of exceptions are you seeing? One thing that differentiates appletviewer from a real browser is that appleyviewer does not enforce any of the security restrictions that apply to applets. So if the applet does something forbidden, security exceptions would be thrown in the browser, but not in appletviewer.
Even I am facing a similiar issue. I have Windows XP and JRE1.5 installed in my PC. I tried accessing http://www.javaranch.com/game/game2.jsp. Instead of applet I get a X symbol on the top left corner. Then I uninstalled JRE1.5 and Installed JRE1.3 I get an error message saying "java.lang.ClassNotFoundException:javaranch.roundup.applets.QuizApplet.class Please help me resolve the issue.
Joined: Mar 22, 2005
Exception are logged in the Java Console. But you said that a NPE was thrown, so you already know where to look for them.