Hi There, Had my mac book about 3-4 months now and so far it has been great. However i just hooked an external monitor up to it and experienced a very strange problem: - My wallpaper changes every 2-3 seconds to a different wallpaper. I have checked in "Desktop and Screensaver" settings and the "Change Picture" is NOT checked on both monitors. I called apple support about this problem and they were frankly - useless. They made me verify there was no problems on the disk - no idea why. And then he put me hold for about half an hour then disconnected me - very annoyed! My OSX version is: 10.5.3 I am not using mirroring. It is an extended desktop. I have tried rebooting but it is still no better. I just hope someone here has an answer to this because it really is very annoying and is making me loose confidence in OSX. Thanks in advance.