If you turn the projector on, hear an audible *POP*, then the screen goes completely dark, you've probably just heard your projector bulb burning out.
Projector lamps use high-pressure discharge technology with a number of components that can fail prematurely or as the lamp ages. Similar to turning on a light switch and hearing an old incandescent bulb burn out, this failure can make a noise.
Most projectors have either an indicator light or message that will indicate the diminishing life of the lamp. If this comes on, it's not a guarantee you need a new lamp right away, but it might be a good idea to purchase a backup for when the time comes.
Resetting the lamp timer with the projector is important after you've replaced the lamp. Without resetting it, you may not be given warning later on when the new lamp is reaching the end of its life.
Once you replace the lamp, consult the owners manual for the projector to determine how to reset the hour counter.
You've dimmed the lights, have a nice projector screen that diminishes or rejects ambient light, and... the projected image is still dull and dim. It's likely the bulb is dying and needs to be replaced.
One way to check this is to turn up the brightness or color on the projector. If the room is as dark as you can make it, and the projector is set to the highest brightness, but the image quality is still dim, then the lamp is on its way out.
As an aside, using the lower-brightness setting on the projector can help extend projector lamp life.
New projector lamps (especially OEM ones) display clear, crisp colors. If you turn on your projector and the colors look like mud, it's likely that the bulb is no longer strong enough to display accurate colors through the projector's color wheel or liquid crystal panel.
Noticing the projected image flicker is a big sign that something is wrong with the lamp. If it hasn't been dropped, exposed to extreme hot or cold, or otherwise damaged, flicker can mean the bulb is about to fail completely. Buy a new lamp sooner rather than later.
