My traffic seems to have stopped today as well, but you should try to use analytics instead of the hubpages account section to track your visits as the HP view tracking may not always be correct.
I can't tell you exactly why your views stopped today. It could be any number of reasons (random off day, weather, end/first of the month, slight fluctuation in search engine rankings etc. etc. etc.)
If you already have a Google analytics account hooked up to your HP, take a look at your views over at least the past month. See what search engine delivers you the most results and where you rank on them for your best hubs/keywords. This might help you narrow it down a bit, hope this helps.