I fixed this once couple years ago, with more than a little guidance from the ZSH-Users list. But it started happening to me again a few weeks ago and I couldn't remember how I fixed it. After searching through my GMail this morning, I found it. Maybe if I put it here I will remember how to fix it next time. And maybe help someone else.

This only happens to me when I use zsh via Cygwin (I also use zsh on OSX and Linux). What happens is that when zsh hits compinitin my ~/.zshrc, it prints a ton of the built-in functions to standard error and that's it. No error, no complaints . . . and no completion. None at all! [See this article][] for a decent idea on how wonderful zsh does completion.

The fix is easy -- manually remove ~/.zcompdump and manually run compinit. That instance of compinit will complete fine. Then start a new shell and you are good to go! Note that you have to manually run compinit-- just starting a new shell won't fix it.

I'm not sure why my ~/.zcompdump keeps getting corrupted . . . maybe because my home directory is on a shared drive?