I had the same problems too. I called them up and the lady told me that if you try to fill in something in the comments section, then you will have problems sending it online. Stupid huh? Why have that section there if you can't even use it??? So, I tried downloading the pdf, and that was giving me problems too. I had to reboot my computer and I finally downloaded the pdf. My luck, there's no space for comments on the paper version either! I just attatched my comments at the end anyways.
The lady at the admisions office is a real sweetie though. Don't hesitate to ask anything if you are having problems.