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5 Video mode not supported / OpenGL Subsystem trouble
Your monitor or operating system can not handle the resolution Urban Terror is trying to run at, or you don't have the correct driver for your video card installed. Get the correct driver here: Nvidia / Ati. If you have the correct driver and suspect the resolution being at fault, open your q3config.cfg with a text-editor and pay special attention to r_mode (resolution), r_fullscreen (toggle fullscreen) and r_displayrefresh (refresh rate). Setting r_mode to 4 = 800x600, 6=1024xx768, 8=1280x1024. Setting r_displayrefresh to 0 makes it use the default from your desktop.