Did reinstalling work for you, leo_ch?
I was having exactly the same problem in TeXniccentre, TeXworks and at the command line - very frustrating.
I was also having this problem: http://www.latex-community.org/forum/vi ... f=9&t=6540
And I have found that this http://permalink.gmane.org/gmane.comp.tex.miktex/6547 solves both.
Hope it works for anyone else with this problem.
MiKTeX and proTeXt ⇒ pdflatex: No .pdf produced
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