On my iPhone4 the navigation at the top of the page clashes with profile navigation stuff:
I use that link back to "discussions" a lot but I can't on my iPhone.
Same thing happens on my desktop when I increase text size -- which I'm doing regularly because fonts on the main discussions page are still too freaking tiny to read.
Same here on my 17" laptop, with the same parameters you state (Zoom to actually be able to see the threads on a main page).
Europe, Middle East and Africa