There's some wierd issues i've been experiencing when trying to make a class.

The program will run however when close it and try to return to the editor, the editor freezes up.
I've noticed the java icon appears when running my code and sometimes if i'm really patient and play with the window (try to highlight stuff or go into full screen using a command prompt window) it will sort of render the editor properly with limited functionality.

When i do close the editor it does give me a blank "do i wish to save" prompt.

Sure, i simply copied the code from the reference library.

I've with it a bit more and noticed that when i run a sketch, the screen jerks around a bit and not only does the processing editor break, so does the java control panel. i'm running java 1.5.0_02 btw.. might that be causing it?
     

// Declare and contruct two objects (h1, h2) from the class HLine
HLine h1 = new HLine(20, 2.0);
HLine h2 = new HLine(50, 2.5);

void setup()
{
 size(200, 200);
 framerate(30);
}

void draw() {
 background(204);
 h1.update();
 h2.update();  
}

class HLine {
 float ypos, speed;
 HLine (float y, float s) {  
   ypos = y;
   speed = s;
 }
 void update() {
   ypos += speed;
   if (ypos > width) {
     ypos = 0;
   }
   line(0, ypos, width, ypos);
 }
}

using xp sp2 and latest processing 0090 .

that code was simple cut and pasted from
http://processing.org/reference/class.html

I'm using the standard java version downloaded from sun.

I'll go and download a 1.4.x version of java and test that out.