In January and February of this year, the entire Math Forum site, including Ask Dr. Math, was first moved from http://mathforum.org/ to https://www.nctm.org/tmf/, and then made inaccessible to non-members, by its current owner, the National Council of Teachers of Mathematics. We are hoping that at least some of this material (the pages we often link to on The Math Doctors) will soon be transferred to new ownership and again be available. We will let you know when such a change occurs.
Until now I have been using my backlog of topics for the blog, accessing pages through The Wayback Machine; but as it has become impossible to search for relevant pages on new topics, I am stopping the weekly posts based on the archive, and will be only posting weekly about recent questions. This coincides with the start of summer, when I am happy to have a little less to do; and it also fits with the original plan to eventually focus on new material. When the archives become available again, I will return to using them, but perhaps less often. There is still a lot of material worth revisiting.