Go to your installation directory,you should see this file named PortableApps.comLauncherRuntimeData-FeedNotifierPortable.ini,open it in notepad and you should find the Status stopped or running or waiting,change it to stopped,copy path in the PluginsDir,open windows explorer ,paste the path and press enter.
you should see the file named runtimedata.ini,change the status to stopped ,then open taskmanager and try to close any dreamweaver portable if running,try a reboot(optional),and the try to run dreamweaver normally.
Source://http://superuser.com/questions/586090/fix-portableapps-com-another-instance-of-is-currently-closing-please-wait