Have you ever worked on a "navigation redesign" that turned out to be a taxonomy problem?
I've seen it happen more than once. The team rebuilds the menu, ships it, and six months later people still can't find anything — because the content underneath was never organized or labeled consistently in the first place.
I wrote up how to tell the two apart, and what to fix first:
The short version: taxonomy decides what things are. Navigation decides how people get to them. One is the structure; the other is a view of that structure.
Curious what you've run into. What gave it away for you that the real problem was deeper than the menu?