This is more a solution than a problem, but if you've updated your apt packages recently, you might come across a parse error that prevents updates from installing. The issue is with the yatex entry in /var/lib/dpkg/available (or wherever dpkg's available packages list is stored on your system).
Locate the yatex entry in this text file, and in the "Recommends" field, you'll notice an email address which shouldn't be there. Example:
Recommends: Ari Pollak <ari@debian.org> | ptex-jtex, tetex-bin
Simply remove the "Ari Pollak <ari@debian.org> |" portion (as the root user, of course), and everything will return to normal. I've already emailed the maintainer about this as well. I believe it's fairly new, so only those upgrading files recently may be affected.
Granted, most of you will know how to fix a problem like this, but it might trip up a newer user, so I've posted it. Hope it helps.
