Can anyone explain why you to do this step in Windows but not in Linux? In Linux I have "One instance when started from file" checked and I can start multiple instance with no problems but in Windows I have to uncheck this.
3. You can also go to Tools -> Preferences -> (set "Show settings" to All") -> Advanced, and uncheck "One instance when started from file".
http://grok.lsu.edu/article.aspx?articleid=14624