I have tried a number of different Java applets (http://www.cs.brown.edu/exploratorie...ryApplets.html) that use Java 3D and run into the same launch error each time:

java.lang.UnsupportedClassVersionError: javax/media/j3d/ImageComponent (Unsupported major.minor version 49.0)
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:539)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:251)
at java.net.URLClassLoader.access$100(URLClassLoader.java:55)
at java.net.URLClassLoader$1.run(URLClassLoader.java:194)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:187)
at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
at java.lang.ClassLoader.loadClass(ClassLoader.java:282)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:274)
at java.lang.ClassLoader.loadClass(ClassLoader.java:282)
at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:302)
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:1655)
at java.lang.Class.getMethod0(Class.java:1901)
at java.lang.Class.getMethod(Class.java:984)
at com.sun.javaws.Launcher.executeApplication(Launcher.java:1312)
at com.sun.javaws.Launcher.executeMainClass(Launcher.java:1270)
at com.sun.javaws.Launcher.doLaunchApp(Launcher.java:1117)
at com.sun.javaws.Launcher.run(Launcher.java:105)
at java.lang.Thread.run(Thread.java:552)

My suspicion is that I accidentally installed bad/outdated Java3D jar files in
System/Library/Java/Extensions.

I've tried every Java update I could find, including JavaForMacOSX10.5Update2, and keep running into the same launch error. Any ideas?