Thanks from me to barbieq25 - I had something in a lower layer selected. For some reason I expected when I created a new layer that the selection would be released. Live and learn.
This thread is, as of 2012-02-16, the top result on Google for "paint.net text not showing". There probably have been many other people that have been helped by this 3 year old post and I am sorry if it is reviving a zombie but this thread is valuable.
Suggestion to those that are receiving use of these suggestions. Take the time to register and then give some love by clicking the green + at the bottom right of the poster that helped you. It is a little token of appreciation.