If you have the above problem, do as the other posters mention and remove the main.out.xml file (don't forget you may need to delete the 'Unparsed aapt error(s)' using the Problems View). After this, you can set your preferences so that it always runs the last application even if you have selected an XML file at the time. Go to Windows -> Preferences -> Run/Debug -> Launching -> Launch Operation -> [select 'Always launch the previously launched application]. Note, that you need to run the application properly at least once (pick from list on Run drop-down menu). Just press the run menu option to start app. after this.