Hello!

The X client versions of GNU Emacs 23.0.x and 23.1.50 do not fail to  
create a preview when my init file contains

	 '(TeX-PDF-mode t)

and they also do not fail when this line is commented. The Cocoa  
variants of the same versions do all fail when this customisation is  
set and they do not fail when it not set (commented). Ghostscript  
8.61 always succeeds to run, and so do all the utilities used by AUCTeX.

The tests were run from auctex-11.85/preview/circ.tex. Systematically  
the first eqnarray environment (line #67ff) was marked as a region to  
be previewed. Caching the preamble was always off, except for a last  
try (which also failed). TeX Live 2008 was last updated a few weeks  
ago. PdfTeX is an updated version without the font cache bug (which  
particularly became "famous" for Mac OS X 10.5, Leopard, users). A  
similar report went to the AUCTeX developers.