After DSS is done, save the file into 16-bit TIFF format, then load this into DPP , play with curves and then convert and save as JPG.
You can have a look at what I am doing, I tried to explain the DPP post processing here (scroll down close to end of page until you see explanation in pictures):
http://www.iceinspace.com.au/forum/s...t=48651&page=2
EDIT: If by accident you used "Per channel background calibration", this will have "colourless" appearance of the background.. and in LP areas will screw-up the colour balance of the whole image.
EDIT 2:
The noise you see is normal consequence of only two images in a stack.
To have noise visibly reduced, you have to have at least 5 images in stack.. but not more than 20, going above this number there is not much difference, but the processing only takes longer.