Red strips/bands in photo

I was out recently trying out my digital rebel xt for some simple night photography. Unfortunately some photos have some faint red strips through them. Not all the photos have some. Can anyone tell me what they are and what is causing it.
Exposure was 30" @ f/4 @ ISO1600. In camera dark frame subtraction was used.
Also there seem to be considerable noise in the photo. Is that normal for a exposure of only 30"? Does dark frame subtraction help reduce noise or does it just take care of hot pixels?
Would noise reduction programs like NeatImage and NoiseNinja work on astrophotos or would it take out faint stars.

Hi Yang, that is not unexpected, I see it too. For me, it happens in two ways- when I use the CF=2 auto noise reduction feature and also when I push development (i.e. levels) too aggresively in photoshop. My current strategy is to shoot with the noise reduction feature off. The subtraction of the dark frames then becomes really tricky. Ideally, I should subtract the dark frame from every frame before combining but I get lazy and end up subtracting a composite dark frame from a composite average frame, which is not that accurate, but even with this approach the banding artifact is minimized.

Ivan