This issue was reported manually by mmirilovic.
It already has 43 duplicates 


Build: NetBeans IDE 6.0.1 (Build 200801291616)
VM: Java HotSpot(TM) Client VM, 1.5.0_13-119
OS: Mac OS X

User Comments:
GUEST: First trying to open a new project, it hung at 25%

Then, trying to add a Main Class to the project, hung again...

nick2k3@gmail.com: this exception occurs whenever I try to create a new class or a new project

gustavpicora: PLEASE HELP ME!!! I CANT EVEN CREATE A PROJECT, I CANT CREATE A CLASS I CANT DO ANYTHING, I UNINSTALLED THE IDE, THE JAVASE6 PREVIEW VERSION, EVERYTING AND NOTHING IT SEEMS TO BE HELPING.
THANKS

GUEST: Can't use it

GUEST: I was trying to create an empty java class file in an package I created some days ago, which was empty at the time of creation of the new java class

edbolson: Trying to create a new main class in a new project

GUEST: Trying to create new java file (impossible now - strange)

GUEST: creating a new interface

GUEST: trying to create a new class file in a netbeans project

GUEST: Creating a new Java class in an existing project.

GUEST: Trying to create a new file within a project.

GUEST: Following Developing General Java Applications - NetBeans IDE 6.0 Tutorial

GUEST: Erzeugen einer neuen Klasse

GUEST: I have type the class name of a class that does not exist yet in my project, in order to use the contextual help to create it.
After clicking on the advice to have that class create, I got the exception.

GUEST: - creating java application

gustavpicora: Im trying to create a class and I can't, and when Im using UML and try to generate the code I receive the same problem. Im under os X Leopard

jmborer: Just trying to create a new Java file. Running Java 1.5 on Leopard

GUEST: adding a class

GUEST: Just trying to create a new class, using the wizard:

File -> new file

cbracken: 1. Expand Source Packages
2. Right-click <Default Package>
3. Select New Class...
4. Enter the name of the class
5. Click Finish

All the buttons on the bottom of the New Class dialog become disabled but nothing happens.  If you change the package, NetBeans gets as far as creating the package, but not as far as creating the class.

GUEST: Creating new Java Class from Template.

This occured on a fresh install, on OS X (Leopard) with the latest Java 6.0 update installed. NetBeans was functioning correctly for the past two months until this patch (or batch of updates) as applied to this machine. Reinstalled NetBeans to see if that would resolve the issue - no dice.

Creating a New Project also fails.




Stacktrace: 
java.lang.UnsupportedClassVersionError: Bad version number in .class file
   at java.lang.ClassLoader.defineClass1(ClassLoader.java:0)
   at java.lang.ClassLoader.defineClass(ClassLoader.java:675)
   at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
   at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
   at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
   at java.net.URLClassLoader$1.run(URLClassLoader.java:195)