Intermittently with the 1.6.6 client, when I try to connect to a server, I would get a dialog box that says "org.lwjgl.LWJGLException: Pixel format not accelerated error". Exiting and starting the World of Minecraft client doesn't make this go away once it appears. Only rebooting the machine will make it go away and make the World of Minecraft client work again. Anybody encounter this issue?