My QuickTime installation keeps breaking after about a month. When I first installed it, it works fine in Safari. But then after a while, it suddenly couldn't play anything. Just keeps saying it doesn't have the software to play the movie, and the software couldn't be found on Apple's servers. WTF? Repairing permissions doesn't help - the only way to fix this is to download QT again and reinstall it. Then it works fine for the next month or so.