Hey, the same thing happened to a post I made that specifically promoted a community project I launched to build a collaborative library for Pianobook. The only external link was to the launch video, nothing offensive and no commercial promotion or anything. It was deleted without notice. I am clueless as to what was inappropriate about it as it was exactly about what I assumed to be the whole spirit of Pianobook. Maybe the forum rules that determine these deletions could be made transparent? Or is this indeed an algorithmic thing?