Sometimes the page was stop loading when using Firefox and caused IE the same problem. I had to restart Firefox so that the problem was fixed. I noticed a suspicious line located at Firefox status bar that said "Transferring data from tongji.baidu.com..." but it didn't show at IE status bar. Is my Firefox hijacked by Baidu? But I checked there were none of any Baidu add-ons installed in my Firefox.
P/S: I'm using Firefox 34.0.5.