WordPress Visual Editor Not Accessible

I ran a snapshot backup on my client’s site before upgrading to WordPress 3.5. Then I updated all WPMU components (theme, plugins) and other plugins.

I then discovered that the Visual Editor on pages and posts was no longer accessible, defaulting to the text tab for HTML entry.

I tried restoring the snapshot backup. But, the Visual Editor is still not accessible.

Help!!!!!!

Thanks.

Neil