Is anyone else having an issue installing the latest El Capitan PB 5. It dowenloads fine, restarts to install then after a few minutes pops up with a message saying 'El Capitan cannot be verified, please restart and try installing again'. I've tried this 5 times but with no success (it has to download the update each time). Running on a 27" iMac 2011, trying to update via App Store. Update worked fine on my rMBP 13". No idea what to do next!