I had this happen after the latest update from Google for Chrome: The "newtab" page stopped working. I have "chrome://newtab/" as my start page. This was getting redirected to "chrome-internal://newtab/" which went nowhere. After some digging, I found that bad (or, I suppose, out of date) extensions can cause this. Open "chrome://extensions/" and turn off all of your extensions. Then, one by one, turn them back on and try newtab. Then just leave the problem child disabled.
I'm posting this here in the hope that the next person who has this happen won't have to search quite so long.