The versions of the software you mention (Texmaker 3.2.1 and libpoppler-qt4-3) are those included in the Precise repositories. However, libpoppler-qt4-4 and Texmaker 3.4-1 are in the Quantal repositories and are listed here and here.
I should check whether you have upgraded properly and run sudo apt-get update to refresh your lists.
However, you can check the Software Sources gui (for example by going to update manager's settings) and see which repositories you are subscribed to, or perhaps edit your sources.list (see below), if inconsistencies have crept into it.
Note (for later readers): you should only carry out the following commands if you have upgraded successfully and are on 12.10.
So, at first open terminal and enter
cd /etc/apt
and then run
sudo sed -i 's/precise/quantal/g' *.list
That should change any erroneous instances of precise to quantal.
(If you wish, you can inspect it manually with gksudo gedit /etc/apt/sources.list)
Now run sudo apt-get update and you should be using the quantal repositories and thus able to install libpoppler-qt4-4 and everything else you want.
