Ok, I have two sites, both 3.5, both with the same plugins, two different themes from RocketTheme (but their forums think it's a WP problem, not an RT problem).
My widget screen on my main site is having the same problem I've seen elsewhere in the forums (can't drag/drop, positions to the right have disappeared entirely, screen options won't activate), but none of the fixes work.
I've deactivated all of my plugins, cleared my browser caches (in Chrome and Firefox), and reset my plugins folder via FTP.
Still the same broken widget screen.
Use Google Libraries, which seems to have helped people in the past, had no effect.
Getting desperate here, any suggestions would be MUCH appreciated!