I have similar widget page 'frozen' issue where you can't drag the widgets on the widgets setup page but, found a fix on the Internet 2-3 months ago that was in the form of a plugin or a config mod that fixed it.
I am configuring a new install with approx 90 plugins installed and 15-20 widgets using plugin central.
I have read the standard uninstall one-by-one to find problem - but that literally kills any time saved using plugin central in which I draw from a core list of plugins that I utilize on each site.
This is maybe my 20th WordPress site - I am a web developer.
Any ideas anyone? This problem is on WordPress version 2.9.1