Folks running ML on a clean build with Safari 6.0 installed and I am getting a complete fail on trying to install extensions - Hardware is a new MBPR. First noted this behaviour trying to install the 1password extension but when this failed I have tried many extensions direct from the Apple webpage and again a big fail. Typical error code is: An error occurred while installing the extension “Twitter for Safari”. Have attempted resetting Safari, clearing caches etc and removing Safari Extension preferences etc and still nothing. Finally took it to a local, ahem, "Genius" and this resulted in him telling me to wait for a few weeks and to bring it back ! Really worth the carpark fee that especially the comment about just using Chrome. Understand Safari 6.0 is new and there may be compatability issues but grateful if anybody could share their own experiences or known fixes for this issue.