Blank Visual Editor

When I try to Edit Page, I have the Visual and Text tab options but both show a blank box even though my page does have content. I am able to get the Text tab working by right-clicking/reloading page once or twice, but no matter what I do the Visual tab always shows a blank box.

I’ve Googled this problem and have tried a number of solutions including disabling all plugins, returning to default theme, adding Use Google Libraries, adding DEBUG and CONCATENATE_SCRIPTS lines to wp-config, etc.

Please help, I’m out of ideas and not all that savvy with this sort of thing. Problem seems to have started with upgrade to 3.5.