Is your mirror out of sync? Check the versions of zlib and lib32-zlib against the one on the home page.
on 03/13/2013 – Made popular on 03/13/2013
What have you done so far? Try moving away your blender config folder, just in case (this should be the first thing to try). Are all dependencies up to date? Check the versions against the website. Is your mirror keeping up with the packages?