$ pstotext /usr/share/doc/libstdc++6-4.3-doc/libstdc++/html/_form0.ps GPL Ghostscript 8.62: Unrecoverable error, exit code 1
...specifically it is failing to open _form0.eps, which does not exist. However, _form0.eps.gz does exist.
$ pwd /usr/share/doc/libstdc++6-4.3-doc/libstdc++/html $ cat _form0.ps 1 1 1 setrgbcolor newpath -1 -1 moveto 111 -1 lineto 111 14 lineto -1 14 lineto closepath fill -148 -654 translate 0 0 0 setrgbcolor (_form0.eps) run $ ls -l *form0* -rw-r--r-- 1 root root 11768 2008-12-31 12:49 _form0.eps.gz -rw-r--r-- 1 root root 150 2008-12-31 12:49 _form0.ps ttfn/rjk