I was browsing the web using Firefox. All of a sudden I couldn't scroll with either one or two finger swipes. Instead of scrolling the tablet now selects texts in the web page. I then tried to scroll by dragging the scroll bar but that didn't work either - the scroll bar just jumped back to the original location. I restarted Firefox and the scrolling worked normally for a moment but then went bad again. What's going on? Please help. Thanks!