title: In Sublime Text 2, Tab button randomly flips between two actions
body: <p>I've tried hard to find an answer for this but I couldn't find one anywhere. </p>
  
  <p>I use Sublime Text 2 and use the Tab button to indent lines and also to select a suggested autocompleted word. However very often pressing the Tab button simply makes Sublime scroll to the end of the file. There seems to be no predictability in whether it chooses to scroll or actually indents a line or autocompletes as I want it to. As far as I can see this behaviour is completely random. Sometimes it indents and sometimes it scrolls. Any ideas as to what makes Sublime scroll down the document and what I can do to prevent this behaviour? </p>