My coauthor sent me a latex file calling for tikz. I find that LaTeX chokes on loading tikz. I am using a freshly installed texlive2012 installation (but I checked same thing happens on TeX Live 2011 an 2010).

Test file:

\documentclass[11pt,reqno]{amsart}
\usepackage{tikz}
\begin{document}
blah
\end{document}


Errors:

(/usr/local/texlive/2012/texmf-dist/tex/latex/amscls/amsart.cls
Document Class: amsart 2009/07/02 v2.20.1
(/usr/local/texlive/2012/texmf-dist/tex/latex/amsmath/amsmath.sty
For additional information on amsmath, use the ?' option.
(/usr/local/texlive/2012/texmf-dist/tex/latex/amsmath/amstext.sty
(/usr/local/texlive/2012/texmf-dist/tex/latex/amsmath/amsgen.sty))
(/usr/local/texlive/2012/texmf-dist/tex/latex/amsmath/amsbsy.sty)
(/usr/local/texlive/2012/texmf-dist/tex/latex/amsmath/amsopn.sty))
(/usr/local/texlive/2012/texmf-dist/tex/latex/amsfonts/umsa.fd)
(/usr/local/texlive/2012/texmf-dist/tex/latex/amsfonts/amsfonts.sty))
(/usr/local/texlive/2012/texmf-dist/tex/latex/pgf/frontendlayer/tikz.sty
(/Users/fgoodman/Library/texmf/tex/latex/pgf/pgf.sty
(/usr/local/texlive/2012/texmf-dist/tex/latex/graphics/graphicx.sty
(/usr/local/texlive/2012/texmf-dist/tex/latex/graphics/keyval.sty)
(/usr/local/texlive/2012/texmf-dist/tex/latex/graphics/graphics.sty
(/usr/local/texlive/2012/texmf-dist/tex/latex/graphics/trig.sty)
(/usr/local/texlive/2012/texmf-dist/tex/latex/latexconfig/graphics.cfg)
(/usr/local/texlive/2012/texmf-dist/tex/latex/pdftex-def/pdftex.def
(/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/infwarerr.sty)
(/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/ltxcmds.sty))))
(/usr/local/texlive/2012/texmf-dist/tex/latex/xcolor/xcolor.sty
(/usr/local/texlive/2012/texmf-dist/tex/latex/latexconfig/color.cfg)))
(/usr/local/texlive/2012/texmf-dist/tex/latex/pgf/utilities/pgffor.sty
(/usr/local/texlive/2012/texmf-dist/tex/latex/pgf/utilities/pgfrcs.sty
(/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/utilities/pgfutil-common.te
x)
(/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/utilities/pgfutil-latex.def
(/usr/local/texlive/2012/texmf-dist/tex/latex/ms/everyshi.sty))
(/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/utilities/pgfrcs.code.tex))
(/usr/local/texlive/2012/texmf-dist/tex/latex/pgf/utilities/pgfkeys.sty
(/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/utilities/pgfkeys.code.tex
(/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/utilities/pgfkeysfiltered.c
ode.tex)))
(/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/utilities/pgffor.code.tex))

(/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/frontendlayer/tikz/tikz.cod
e.tex
(/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/libraries/pgflibraryplothan
dlers.code.tex
/usr/local/texlive/2012/texmf-dist/tex/generic/pgf/libraries/pgflibraryplothand
lers.code.tex:104: Undefined control sequence.
\pgfsetplottension ...ttension {\pgf@sys@tonumber
\pgf@x }
l.104 \pgfsetplottension{0.5}

?
Process aborted

-
Welcome to TeX.sx! A tip: If you indent lines by 4 spaces, they'll be marked as a code sample. You can also highlight the code and click the "code" button (with "{}" on it). –  Joseph Wright Aug 14 '12 at 19:14
I had this problem too, once upon a time when I was using tetex. When I switched completely to texlive everything was fine, but that transition period with some locally installed packages, some tetex, and some texlive... That was a messy time. –  Jack Schmidt Aug 14 '12 at 21:50

(/Users/fgoodman/Library/texmf/tex/latex/pgf/pgf.sty

in the log file. You have a local copy of pgf.sty, probably an old one, which is being loaded in preference to the 'system wide' one which will be in /usr/local/texlive/2012 (or other year, as appropriate). Try moving the old file outside of ~/Library/texmf`: indeed, you may have other old files there too, so check your log carefully.