I find when a composition won't render it's usually a clip on the timeline (or really large still images in my case)
For instance I do video board game reviews and I have issues rendering from Premier CS5 when the 9 megabyte still images are on the timeline.
Try moving half the clips to a layer and turning them off(click the eye next to the layer) then trying to render, if it still fails turn that layer back on and the other layers off.
Or rendering out a smaller segment of the timeline.
I think CS4 comes with media encoder.
If your using the media encoder try not using it and rendering directly from Premier. If your not using the media encoder try using it.
(this might be your issue ? http://frankieloscavio.blogspot.ca/2009/03/fixing-adobe-media-encoder-export.html )
Have you been able to render from premier before?
Have you patched it with the latest updates from Adobe?
Hacked copies of premier tend to have more bugs because you can't install the updates and fixes they release.