Howto: Fixing NewTabURL Rated 5 out of 5 stars
I got it working by doing the following:
If you have done any of the about:config / browser.newtaburl changes, then undo them.
browser.newtab.url - should be blank
browser.newtabpage.enabled - should be true
Now the Add-On works as expected, including the "URL from Clipboard"
Thanks for all the kind words. I just installed a fresh copy of FF15 and NewTabURL and it still is not fixed. Funny, I searched, found this thread, and to my amazement, I had already figured it out...glad I posted it as I forgot I fixed it. The best part of this add-on compared to all other solutions is "Open URL from Clipboard, Load only once"
The issue is not with the author, it is with Firefox. They change the about:config code and that is the key piece that broke the add-on. If you perform the simple above steps, it works fine.
I am not sure if the Author could hack the add-on to change those about:config entries on install, probably so, I just have never written an add-on for FF. No matter, it works, and thanks to all of you for the thanks, and even for the translation!