Alright, I am having a similar problem to that referenced here:
The solution supposedly is to rollback file-roller in gnome (I'm 13.04 on a 64bit system), and I while I can:
I'm not sure which version to install instead since the one listed in the link I provided is for 12.04 and I doubt they are compatible. Any known fixes/help available? I really don't want to have to boot Windows every time I want to move textures into a .jar.
sudo apt-get remove/purge file-roller