Ubuntu 9.04,64-bits,ext4
ATI Radeon Xpress 1100
I think its probably a driver problem… anyone?
It occurs in all Tests
19/04/2009 22:35:52 com.jme.app.BaseGame start
INFO: Application started.
19/04/2009 22:35:52 com.jme.system.PropertiesGameSettings <init>
INFO: PropertiesGameSettings created
19/04/2009 22:35:52 com.jme.system.PropertiesGameSettings load
INFO: Read properties
19/04/2009 22:35:59 com.jme.system.PropertiesGameSettings save
INFO: Saved properties
19/04/2009 22:35:59 com.jme.app.BaseSimpleGame initSystem
INFO: jME version 2.0 Stable (r4093)
19/04/2009 22:35:59 com.jme.input.joystick.DummyJoystickInput <init>
INFO: Joystick support is disabled
19/04/2009 22:35:59 com.jme.system.lwjgl.LWJGLDisplaySystem <init>
INFO: LWJGL Display System created.
19/04/2009 22:35:59 com.jme.system.lwjgl.LWJGLDisplaySystem initDisplay
SEVERE: Cannot create window
19/04/2009 22:35:59 class com.jme.system.lwjgl.LWJGLDisplaySystem initDisplay()
SEVERE: Exception
org.lwjgl.LWJGLException: Could not query best cursor size
at org.lwjgl.opengl.LinuxDisplay.nCreateBlankCursor(Native Method)
at org.lwjgl.opengl.LinuxDisplay.createBlankCursor(LinuxDisplay.java:1056)
at org.lwjgl.opengl.LinuxDisplay.createWindow(LinuxDisplay.java:432)
at org.lwjgl.opengl.Display.createWindow(Display.java:308)
at org.lwjgl.opengl.Display.create(Display.java:839)
at org.lwjgl.opengl.Display.create(Display.java:767)
at com.jme.system.lwjgl.LWJGLDisplaySystem.initDisplay(LWJGLDisplaySystem.java:422)
at com.jme.system.lwjgl.LWJGLDisplaySystem.createWindow(LWJGLDisplaySystem.java:143)
at com.jme.app.BaseSimpleGame.initSystem(BaseSimpleGame.java:380)
at com.jme.app.BaseGame.start(BaseGame.java:70)
at jmetest.terrain.TestFluidSimHeightmap.main(TestFluidSimHeightmap.java:70)
19/04/2009 22:35:59 com.jme.app.BaseSimpleGame initSystem
SEVERE: Could not create displaySystem
com.jme.system.JmeException: Cannot create window: Could not query best cursor size
at com.jme.system.lwjgl.LWJGLDisplaySystem.initDisplay(LWJGLDisplaySystem.java:440)
at com.jme.system.lwjgl.LWJGLDisplaySystem.createWindow(LWJGLDisplaySystem.java:143)
at com.jme.app.BaseSimpleGame.initSystem(BaseSimpleGame.java:380)
at com.jme.app.BaseGame.start(BaseGame.java:70)
at jmetest.terrain.TestFluidSimHeightmap.main(TestFluidSimHeightmap.java:70)
i think it could be a 64 bit problem though i’m unsure I don’t see ur video card in the hardware compatibility list but its slightly outdated and under modified anyway 
It was probably a 64 bit error in lwjgl, as Bonechilla had predicted.
I posted this in lwjgl forums, so Elias recommend me to use the nightly build.
Done and everything is smooth again.
People using 64 bits platforms, i recommend that too.
Lwjgl Topic: http://lwjgl.org/forum/index.php/topic,2890.0.html
Nightly Build: https://www.newdawnsoftware.com/hudson/view/LWJGL/