Based on your pastebin I can safely say that you have a service running on port 8080 other than Mendix. Possibly apache or nginx? You seem to have a bunch of .swf files hosted there which don't belong to mendix. You can try searching for those files on your harddrive, which might give you a clue as to which other service you have running.
You'll have to either turn off this service or run Mendix off of a different port and visit it there. If you change the port in the modeler you will also need to surf to the appropriate port in your browser. For instance, if you change the port to 8081, you should open http://localhost:8081 to get to the app.
Are you going to the correct port? It's 8080 by default. There's a button in the modeler that will open your browser on the correct port automatically.