It's probably just that the first time you got the message was on the PM submitted page, and when you continued sending PMs, your browser was loading the cached version of the page. That's why the other browsers worked -- because they didn't have the page cached. That happens to me all the time on my iPhone when I try loading a page during an update. And I use Chrome to view the site on my laptop, and I haven't had any trouble this week because I never tried loading a page during an update with it. That's all it was. Chrome should work just fine. It's not a bug.