I still haven't found out how to effectively solve Overfull \hbox (0.80913pt too wide) has occurred while \output is active warnings.
For instance, this piece of latex generates such a warning and I am stumped why:
\newcommand\Header{%
\noindent\makebox[\textwidth][l]{
\parbox{0.5\textwidth}{\contactinfo}
\parbox{0.5\textwidth}{%
\hfill\includegraphics[height=25pt]{logo}}}\par\vskip1ex%
\par\ColTopRule\par}
\contactinfo is defined as follows:
\newcommand\contactinfo{\fontsize{8pt}{8}\selectfont\headerfnt Streetname 12324 \\ PostalCode City \\ +31655555555555}
Error:
*geometry detected driver: pdftex*
<logo.eps>
Overfull \hbox (0.80913pt too wide) has occurred while \output is active
[]
[1] <logo.eps>
Overfull \hbox (0.80913pt too wide) has occurred while \output is active
[]
[2] <logo.eps>
Overfull \hbox (0.80913pt too wide) has occurred while \output is active
[]
[3] <logo.eps>
Overfull \hbox (0.80913pt too wide) has occurred while \output is active
[]
Expected output is:
Streetname 12324 here comes
PostalCode City the logo
+31655555555555 right aligned
-----------------------------------------------------------------
I mean, both boxes have a length of 0.5\textwidth, the text is obviously smaller than this, as is the logo. How come it still generates such a warning? And how can I found out why?

%. E.g.\noindent\makebox[\textwidth][l]{%– Marco Daniel Apr 13 '12 at 11:50\newcommand\Header{% \noindent\makebox[\textwidth][l]{ \parbox{0.5\textwidth}{\contactinfo} \parbox{0.5\textwidth}{% \hfill\includegraphics[height=25pt]{logo}}}\par\vskip1ex% \par\ColTopRule\par}error remains
– grrrbytes Apr 13 '12 at 11:54\makebox[\textwidth]{...}doesn't care if you put something larger than\textwidthin it. So I doubt that the problem is from the content. I guess that you either have a additional space at the place where you use your\Headercommand or a non-zero\parfillskipvalue. Make a complete example. – Ulrike Fischer Apr 13 '12 at 12:37\ColTopRule? a minimal working example (MWE) always helps... – David Carlisle Apr 13 '12 at 19:49