problema e non so cosa sia

All’improvviso, tentando di compilare, LaTeX mi dà questo problema, senza che io abbia cambiato nulla nel codice. Tra l’altro, non so cosa significhi né cosa devo fare per eliminarlo.

`This is pdfTeX, Version 3.1415926-1.40.11 (Web2C 2010)
restricted \write18 enabled.
entering extended mode
(./Tesi.tex
LaTeX2e <2009/09/24>
Babel and hyphenation patterns for english, dumylang, nohyphenation, ge
rman-x-2009-06-19, ngerman-x-2009-06-19, afrikaans, ancientgreek, ibycus, arabi
c, armenian, basque, bulgarian, catalan, pinyin, coptic, croatian, czech, danis
h, dutch, ukenglish, usenglishmax, esperanto, estonian, ethiopic, farsi, finnis
h, french, galician, german, ngerman, swissgerman, monogreek, greek, hungarian,
icelandic, assamese, bengali, gujarati, hindi, kannada, malayalam, marathi, or
iya, panjabi, tamil, telugu, indonesian, interlingua, irish, italian, kurmanji,
lao, latin, latvian, lithuanian, mongolian, mongolianlmc, bokmal, nynorsk, pol
ish, portuguese, romanian, russian, sanskrit, serbian, slovak, slovenian, spani
sh, swedish, turkish, turkmen, ukrainian, uppersorbian, welsh, loaded.
(c:/texlive/2010/texmf-dist/tex/latex/base/report.cls
Document Class: report 2007/10/19 v1.4h Standard LaTeX document class
(c:/texlive/2010/texmf-dist/tex/latex/base/size12.clo))
(c:/texlive/2010/texmf-dist/tex/latex/base/fontenc.sty
(c:/texlive/2010/texmf-dist/tex/latex/base/t1enc.def))
(c:/texlive/2010/texmf-dist/tex/latex/base/inputenc.sty
(c:/texlive/2010/texmf-dist/tex/latex/base/utf8.def
(c:/texlive/2010/texmf-dist/tex/latex/base/t1enc.dfu)
(c:/texlive/2010/texmf-dist/tex/latex/base/ot1enc.dfu)
(c:/texlive/2010/texmf-dist/tex/latex/base/omsenc.dfu)))
(c:/texlive/2010/texmf-dist/tex/generic/babel/babel.sty
(c:/texlive/2010/texmf-dist/tex/generic/babel/italian.ldf
(c:/texlive/2010/texmf-dist/tex/generic/babel/babel.def)))
(c:/texlive/2010/texmf-dist/tex/latex/amsmath/amsmath.sty
For additional information on amsmath, use the `?' option.
(c:/texlive/2010/texmf-dist/tex/latex/amsmath/amstext.sty
(c:/texlive/2010/texmf-dist/tex/latex/amsmath/amsgen.sty))
(c:/texlive/2010/texmf-dist/tex/latex/amsmath/amsbsy.sty)
(c:/texlive/2010/texmf-dist/tex/latex/amsmath/amsopn.sty))
(c:/texlive/2010/texmf-dist/tex/latex/amsfonts/amsfonts.sty)
(c:/texlive/2010/texmf-dist/tex/latex/amsfonts/amssymb.sty)
(c:/texlive/2010/texmf-dist/tex/latex/stmaryrd/stmaryrd.sty)
(c:/texlive/2010/texmf-dist/tex/latex/esint/esint.sty)
(c:/texlive/2010/texmf-dist/tex/latex/xcolor/xcolor.sty
(c:/texlive/2010/texmf-dist/tex/latex/latexconfig/color.cfg)
(c:/texlive/2010/texmf-dist/tex/latex/pdftex-def/pdftex.def
(c:/texlive/2010/texmf-dist/tex/generic/oberdiek/infwarerr.sty)
(c:/texlive/2010/texmf-dist/tex/generic/oberdiek/ltxcmds.sty)))
(c:/texlive/2010/texmf-dist/tex/generic/mathdots/mathdots.sty)
(c:/texlive/2010/texmf-dist/tex/latex/graphics/graphicx.sty
(c:/texlive/2010/texmf-dist/tex/latex/graphics/keyval.sty)
(c:/texlive/2010/texmf-dist/tex/latex/graphics/graphics.sty
(c:/texlive/2010/texmf-dist/tex/latex/graphics/trig.sty)
(c:/texlive/2010/texmf-dist/tex/latex/latexconfig/graphics.cfg))) (./Tesi.aux
! Undefined control sequence.
l.85 \@writefil

?`

Grazie mille in anticipo