I just posted this to http://dev.processing.org/bugs/
but I thought others might be interested in this ...

After drawing a sketch using OPENGL
and then calling noLoop() ...
if you call  saveFrame("frame.tif")
or even just  loadPixels()
then Processing will crash with this error:
// Invalid memory access of location 00000000 eip=96cac314

I hope we can get this bug fixed soon,
since I presume lots of people will want to:
(1) draw in a loop
(2) stop the drawing loop
(3) save the image

-- djones

Code:

// bug_saveFrame_noLoop
//
// this program illustrates a Processing bug
// in the following situation:
// (1) using OPENGL
// (2) after calling "noLoop()"
// (3) call "saveFrame()" or "loadPixels()"
// this crashes the program with this error:
// Invalid memory access of location 00000000 eip=96cac314

import processing.opengl.*;


void setup() {
  size(400,400,OPENGL);
  println("To test this Processing/OPENGL bug, ...");
  println("(1) press 'n' to call noLoop()");
  println("(2) press 's' to call saveFrame()");
  println("(3) press 'p' to call loadPixels()");
}

void draw() {
  fill(random(0,255));
  ellipse(random(0,width),random(0,height),8,8);
}

void keyPressed() {
  if (key == 'n') {
    println("noLoop()");
    noLoop();
  } else if (key == ' ') {
    println("loop()");
    loop();
  } else if (key == 's') {
    println("saveFrame()");
    saveFrame("frame.tif");
    println("saveFrame success");
  } else if (key == 'p') {
    println("loadPixels()");
    loadPixels();
    println("loadPixels success");
  }
}