Comment 4 for bug 359862

I ran into this problem last night, and here's my hasty work-around:

Purge all the currently installed acroread packages.

There are three acroread files in /var/apt/archives that need to be forefully removed:
/var/cache/apt/archives/acroread-dictionary-en_8.1.3-0medibuntu0.8.10.2_i386.deb
/var/cache/apt/archives/acroread-l10n-en_8.1.3-0medibuntu0.8.10.2_i386.deb
/var/cache/apt/archives/acroread_9.1.0-7intrepid1_i386.deb

This can be done with:
sudo rm -rf /var/cache/apt/archives/acroread*

*NOTE: If you're not familiar or comfortable with sudo rm -rf, don't ever touch this command -- its the command-line equivalent of a wildfire, tsunami, hurricane, tornado, and famine, and leaves nothing behind.*

Then run
sudo apt-get update

And
sudo apt-get install acroread

You'll be asked to configure it, but it then installs without issue.