Blank animation png output

Frames render in viewport fine when I go to save file they are all black, in both CPU and GPU mode. Also first time I click on render animation button, blender closes, open it back up hit render animation and its fine again until I stop and start. Windows 8.1 GTX 760 4GB intel i7 4770. System worked fine with 2.69 (poet and didn’t know it!)

Frames render in viewport fine when I go to save file they are all black,
Supply an example blend file (http://www.pasteall.org/blend/), there are numerosu possibilities so easier just to see what you scene looks like

Are you using the compositor ? If so check the nodes or disable in Render / Post Processing
Are you using the video sequencer ? Check nothing is loading or disable in Render / Post Processing
Check render layers are correct