Download problems

Hey, i wanted to do the Steam Treasure Hunt, but i have a little problem with downloading the "underground Demo" My problem is that what its downloading reeaaly slow, i let it download for 5 hours.. And its still only 1% can some1 help me or atleast tell me what to do, because its kinda annoying that i cant do it because something is blocking it... And its not because of my internet.. Its fine.