Hello,
The same thing happened to me this morning, and I found a solution. After re-installing to no avail, I finally realised that the dock was actually starting and continually crashing. I also noticed that I had downloaded a .jpg file that for some peculiar reason refuses to 'play nice' with quick view. In fact that file has crashed my finder every time I have tried to quick view it. Anyway, when I realised that I had a copy of that file in my downloads stack, I realised that it was crashing the dock, because it could not render an icon of that file to show as the stack icon. The problem was solved when I deleted the file from the 'downloads' folder in the finder (its in the user home i think), and the default stack icon returned, with my dock.
I am not sure that this will help, but at least you could give it a go. Try find any files in a stack that are not working well with with quick view, and see if removing them from a stack brings your dock back.
Take care,
-Sami