[ BUILD # : 200510131600 ]
[ JDK VERSION : 1.5.0_05 ]

Steps to reproduce:

1/ New Project->General->Java Application - defaults are fine.
2/ Paste the following code:

package myapp;

public class Outer {
    class Inner<T extends Number> {}
    
    public static void main(String[] args) {
        Outer.Inner<Integer> oi = Outer.new Inner<Integer>();
    }
}

and you'll see the attached ClassCastException. 

To get rid of the error popup window, quickly remove the new keyword after Outer class, but it's very tricky.