Folks, curly one here. Have just upgraded my imac to Mountain Lion this week. We have two logon accounts - 1 for myself & wife, another for the kids. All working well except for some bizarre reason under the kids profile, youtube and yahoo will not open under either safari or firefox. These websites open without issue under our own Dad/mum logon profile. All other websites open fine for the kids, so why youtube & yahoo a problem? Can't get through to the apple helpline (too busy) and our ISP provider was clueless. Thoughts welcome.