When the version 9 of the Adobe Reader was released last years summer, Adobe did not publish a Linux version. Now the version 9.1 of the reader has been relased for Linux and Solaris, including an important security patch, version 9.0 was skipped. To get information about its features and for download visit adobe.com or the Adobe Reader Blog announcement, for short german information you could visit golem.de, techniknews.com or Dogan’s Solaris blog.

Robin Fairbairns has released the version 2.16a (2009/03/28) of the rotating package, there he has corrected a bug introduced in v2.16 (2009/03/16). Using 2.16 you could get the error message ! A <box> was supposed to be here.
<to be read again>
\ignorespaces when using a rotating environment like rotate or sideways.
The bug and it’s cause were discussed by Jürgen Spitzmüller and Ulrike Fischer (”…rotating uses \color@hbox in a context where a box command is needed…”) on comp.text.tex and Robin fixed it by adding

\AtBeginDocument{%
  \providecommand\color@hbox{\hbox\bgroup}%
  \providecommand\color@vbox{\vbox\bgroup}%
  \providecommand\color@endbox{\egroup}%
}

to 2.16.

If you encounter this error just update the rotating package, perhaps by a package manager like mpm or tlmgr. Thanks to Jürgen, Ulrike and Robin for the quick solution.

This topic was also discussed on mrunix.de.