With the introduction of the ViewRenderer component into the Zend Framework has come all sorts of troubles for all sorts of developers. Thankfully, there's posts like this one from Pádraic Brady that helps out with some of the more common issues people are seeing (a problem/solution approach).
The ViewRenderer "action helper" is the class Zend_Controller_Action_Helper_ViewRenderer. It's primary purpose is to facilitate the automated rendering of View scripts (templates) based on the generally accepted Zend Framework conventions. It's these conventions which will cause a lot of people grief, since the previous reliance on programmers defining the template to render has likely led to inconsistent template names.
Included in the post is a list of some of the common issues developers have including "ViewRenderer is enabled by default", "Inconsistent location of template files" and "Reusing template files across Controller actions". For each, he's included a "quick hit" solution to get you back on the straight and narrow road to having a nicely working Zend Framework application.