Widgets drag & drop don't work

Hello,

I am using wordpress 3.0, Yesterday when I wanted to add some widgets to the right side column the drag& drop didn’t work, more exactly I drag them and drop them over the designated spot but they are not saving there.. Someone told me to deactivate all plugins to see if one of them causes this problem, I’ve done that but still no change..

Anybody had same issue? How can I fix this?
Thanks!