On Processing 1.0.7 and 1.0.8 under certain (and unclear) circumstances the
OpenGL library won't load on Mac OS X and Windows XP. This is NOT a driver
problem because after moving the OpenGL lib to the "sketchbook/libraries/"
folder the problem stops happening.

More info in these threads of the discourse:

http:// processing.org/discourse/yabb2/YaBB.pl?num=1255097207 for Mac OS X
http:// processing.org/discourse/yabb2/YaBB.pl?num=1253482788 for Windows XP

Error message on Win XP:

Message area:
You need to use "Import Library" to add processing.opengl.PGraphicsOpenGL
to your sketch.

Console message:
Exception in thread "Animation Thread" java.lang.RuntimeException: You need
to use "Import Library" to add processing.opengl.PGraphicsOpenGL to your
sketch.
at processing.core.PApplet.makeGraphics(PApplet.java:1192)
at processing.core.PApplet.size(PApplet.java:998)
at processing.core.PApplet.size(PApplet.java:958)
at sketch_oct20a.setup(sketch_oct20a.java:23)
at processing.core.PApplet.handleDraw(PApplet.java:1402)
at processing.core.PApplet.run(PApplet.java:1327)
at java.lang.Thread.run(Thread.java:619)


Tested code on Win XP:

import processing.opengl.*;

void setup() {
size(200,200,OPENGL);
}

void draw() {
background(0);
}

When the error happens this very simple code fails to execute.

Tested on an old Laptop Toshiba Tecra A6 Windows XP based, Intel Centrino @
1.6GHz, 512 MB RAM. my newer computer does not commit the mistake (Win XP
Intel Based Motherboard w/ Intel core 2 duo @2.4GHz 1GB RAM).

1) quit processing, and put the opengl library back to its original location.

2) move sketchbook/libraries to another location, so that no other
libraries are installed.

3) start processing, and try using the opengl library again.

it will probably work, and the problem is likely that another library you
have installed, in violation of the library guidelines, includes opengl or
jogl inside it.

no followup, closing bug.