I'm not sure about the 1000D, but some other cameras from Canon have this problem too. It is not a camera problem. You are probably just having problems with a camera mode.
At night time, when your room is lit by normal room lighting like CFL or bulbs....do the following:
Set camera to manual mode.
Set f-number to f/8 or f/6.3...something between these.
Set shutter speed to 15 sec.
Keep flash off.
Take a photo. Try to keep your hand reasonably steady. See what you get. Of course you'd get a blurred photo but it should be bright enough. If it is still coming out dark, then there is a problem with your camera or lens aperture. Time to visit the service center for advice.
MANY Canon cameras, especially super zoom models and certain DSLR models...they internally limit the shutter speed in Av (aperture priority) mode to 1 sec. So if you try indoor shooting, almost all your photos would be underexposed.
Let me know what happened with this test. :)
55-250mm standard lenses. Dual tube macro flash and external speedlit...