Problems inserting media following upgrade to 3.1.1

Just completed an upgrade to version 3.1.1

Everything seems to be working fine apart from the buttons to insert media into a post. The buttons are displayed but are unresponsive, or if I’m in working on the post in fullscreen mode then the screen greys out but no dialogue box is displayed.

I have changed to different themes to check if it was a theme code problem but the same happens.

The media library uploader works fine, so I am inserting media manually through HTML.

Can anyone help?

Chris