I am having the same problem, although last week I entered the basic information with no difficulty.
I read your suggestion above, Gabriel, but I get the same result on Internet Explorer. I also noticed on the page on both browsers that the secure padlock icon has a red X on it and the https has a red slash through it.
The only other U-file page I can get to informs me that I already have a session open, although I don't. I have restarted my laptop but get the same results.
The first time this occurred earlier today I noticed that although the URL displayed as it normally does, the page was blank and had a URL address which started off with something similar to SaltarSmart so I closed down the browser and ran Spybot which did not turn up SaltarSmart as one of the Adware results to kill.
Thanks for whatever suggestions you can offer.
J L