Broken libc6 makes system unbootable when I install packages via apt-get

I tried to install Skype on my amd64 Debian 7, after believing the page that told me to upgrade libc6 and allow the x86 architecture. When I started downloading such packages and upgrading libc6 my system broke and at boot I kept getting this message:

Inconsistency detected by ld.so: dl-close.c: 743: _dl_close: Assertion map >l_init_called' failed! (Which happens to be the same one when I type /lib/libc.so.6 on the terminal)

I used a rescue disk, erased all the x86 packages and deleted the x86 architecture but if I install something from apt-get, the system breaks again and the OS wont boot until the ld.so.cache file is deleted.

If ldd --version is run on the terminal the output is: ldd (Debian EGLIBC 2.13-38+deb7u6) 2.13

What should I do in order to be able to install packages again via apt-get without having to rescue the system each time afterwards?