This is going to sound ridiculous... My wife's Macbook had the very annoying behavior in Gmail / Firefox where if you pressed tab after writing the email, it wouldn't put the focus on the 'send' button, so if I did tab, enter, it would actually discard my email. In my Mac Pro, it worked fine. For almost a year. Now it's driving me crazy and behaving like my wife's Macbook. What's the deal?