Recent release of libpng and libtiff arrived into main Arch repo and require a massive update for all packaged that depend on it. This update is dangerous and may or may not break your system. If you have installed packaged from AUR you should check it and rebuild if they depend on libpng or libtiff - mostly cairo-* packages, else they might not work.
Check with pacman -Qm for foreign packages.
WARNING: All ArchBang Linux users will be affected, because ArchBang uses cairo-ubuntu packge.
QUICK FIX: sudo pacman -S cairo and accept package replacement. make this fix immediately after the update or your system will ends broken very soon or after reboot.
If your system is broken and you cannot login into normal graphical environment, don't worry. just log into console and fix your system in text mode using quick fix above, then reboot. Good Luck.