A glowing blue light in your Wii's disc slot usually indicates that the WiiConnect24 service is active or that you have unread messages. This is a normal function and doesn't necessarily indicate a problem. However, if the light remains on constantly and you're not using WiiConnect24, or if it's accompanied by other issues, it may suggest a connection problem or a software glitch. Try checking your WiiConnect24 settings or restarting your console.