Image uploader not working since upgrade to 3.5.1

When I upgraded the latest version the Visual Editor wasn’t working nor was the add media/image uploader – since reading various posts about this problem I have changed the config file which has now solved the issue of the visual editor part but the image uploader still is unresponsive.

I have tried disabling plugins, themes, etc – all the normal stuff – but still nothing.

What to try next?