pstool stopped working

In some figures I create for my thesis I want to replace the labels and such using the same font and size as in the rest of the thesis. A couple of month ago I already used psfrag and pstool (with pdflatex). But now I cannot get it working. I did not changed any files (using a version control system, so I'm pretty sure).

The following mini example produces the same error as in my thesis:

\documentclass{article}
\usepackage{pstool}

\begin{document}
\begin{figure}
\centering
\psfragfig*{Inverses_Pendel}
\end{figure}
\end{document}

In the same directory are the files Inverses_Pendel.eps and Inverses_Pendel.tex. Inverses_Pendel.tex contains the following content:

\psfrag{T}[cc][cc]{$Test$}

And here is the error:

Package pstool Warning: Execution failed during process: ps2pdf "-dAutoFilterColorImages=false" "-dAutoFilterGrayImages=false" "-dColo rImageFilter=/FlateEncode" "-dGrayImageFilter=/FlateEncode" "-dPDFSETTINGS=/pre press" "Inverses_Pendel-pstool.ps" "Inverses_Pendel.pdf" This warning occurred on input line 7.

! Missing $inserted.$ l.7 \end {figure} ? ! Emergency stop. $l.7 \end {figure} End of file on the terminal! It's such a generic error, I don't even know where to start searching. I'm using MikTeX 2.9. I'm passing the -shell-escape option. - The "Missing$" error looks a bit if the underscore in your file name leds to errors. But this is perhaps only a side effect. If you get an error also when you remove the underscore you should put the eps and the tex somewhere for download so that other can makes tests. –  Ulrike Fischer Aug 1 '12 at 7:48
@Ulrike Fischer - Removing the underscore fixed my problem with the "Missing $" error. Thank you for that! But now the generated pdf contains a red text message: "An error occured processing graphic './InversesPendel'" ... I will do a some research first, and update the question, if I dont get that error fixed. – PetPaulsen Aug 1 '12 at 8:14 @Ulrike Fischer - Solved my other problem too. It seems my MiKTeX installation was broken, ps2pdf didn't work. When you make your comment an answer I would accept it, because it solved my initial problem ("Missing$" error). –  PetPaulsen Aug 1 '12 at 9:11

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