Consumer a/v gear, like DVD's, cable boxes and TV's, handle video differently than PC's and PC Monitors. PC's and PC Monitors exchange information about the resolution and capabilities of the monitors using EDID, and the PC's figure out automatically what type of monitor is connected to which video connector (ie VGA, DVI, etc.). Consumer a/v gear generally does not work like this; you tell the device what resolution to output usually with a switch, and it outputs the same video on all connectors at the same time.
This often leads to frustration when using a home theater PC because when you connect the PC to a TV the PC is expecting to get valid information from the TV using EDID, but most consumer TV's do not report this correctly, and so the PC's often times end up outputting the wrong resolution, or not correctly detecting which connector is active. To get it to work can be complicated, using utilities like PowerStrip for Windows, or editing Modeline's in Linux.
Since LinuxMCE is intended to mainly be used with a PC we made it act like a normal consumer a/v device. It does not use EDID or try to talk to the TV or monitor. It just outputs whatever resolution you tell it to on whatever connector you specify. This is done using the video/audio setup wizard. This wizard is started automatically the first time the system boots, and does not start again. If you want to change the settings, you can restart the A/V wizard by choosing Advanced, Advanced, A/V Wizard from the main LinuxMCE menu, or during bootup you can either hold down the shift key on the keyboard, or press the a/v menu button on the remote to make A/V wizard start that boot. During bootup you will hear a series of escalating beeps to tell you when LinuxMCE is monitoring the Shift & A/V Menu keys. Hold the keys and A/V Wizard will start. When you hear the descending beeps that means it's too late; the bootup has already gone past the AV Wizard check and LinuxMCE has started.
When A/V Wizard starts it always outputs 640x480 on the VGA connector. So, if you are not using the VGA connector, you will likely see a blank, black screen when A/V Wizard starts, even if you previously saw the Kubuntu boot splash. You will know that the A/V Wizard is running because you hear a series of beeps. When you hear those beeps, if you have video, proceed to complete the A/V Wizard. If you do not, press the number 1 through 5 on the keyboard or the remote control to switch to the connector that is active. Wait about 15 seconds, and you will hear that same sequence of beeps telling you that A/V Wizard has now restarted using the connector you specified. If you don't hear the beeps after 15 seconds, press the number for your connector again. If you do hear the beeps, but you still don't see a picture, it's possible that the display you're using cannot handle 640x480. If so, then press the number 6-9, and 0, and shown below to select a resolution. Again, 15 seconds later, you'll hear the beeps when A/V Wizard is running. If you need to choose a connector besides the default VGA, press the 1-5 key and wait until you hear the beeps again before choosing another connector or resolution.
Once you have a picture you can proceed to complete the A/V Wizard and resize your user interface to fit your screen, choose your audio outputs and so on.
A/V Wizard makes the process a bit more complicated for normal PC users that are using PC Monitors and used to having the video card automatically figure out the correct connector and resolution. But it's the only way to make it simple to use a home theater PC with a consumer TV and still HD video without needing to mess with complex utilities.
Keys for choosing a connector: 1: DVI 2: VGA 3: Component 4: Composite 5: S-Video
Keys for choosing a resolution: 6: 640x480 7: 1024x768 8: 720p 9: 1080i 10: 1080p