Widgets won't drag and drop

I’ve seen this problem written about many places and tried all the solutions but so far it still won’t work for me.

Widgets won’t drag and drop and when I try to click the Screen Options button no other links come up so I can’t enable the accessibility.

I’m having the problem in Firefox, IE and Chrome.

I’ve deactivated all my plugins. I’ve uninstalled and reinstalled WordPress and Thesis. I’ve changed themes. I’ve updated Java.I’ve checked and my host doesn’t run proxy servers. I’ve rebooted my modem.

I was running WP 3.3 and Thesis 1.8.2 but tried upgrading both and that didn’t do it.

It doesn’t happen on the 3 other websites I manage- just this one.

What else can I try?

Thank you!