Most of the time, issues arrive after a browser updates itself. Normally, this happens behind the scenes. That is where I have seen issues come about that were not present before. For example, at the pcengine free forums with chat. I had been using Opera with no problems. After a recent update, I had the exact same issue that munch is having with youtube. It kept going back to the main sign in, telling me my sign in info was invalid. I first thought it was a site issue, but tried using Firefox and IE with no issues. FireFox seems to be the win all browser for me, altho Opera is such a pretty one.. I love the way its set up.