In Firefox 8.0 on Ubuntu 11.10, when I drag a site from the Address Bar to the Bookmarks Toolbar (in hopes of creating a new bookmark) the entire system freezes for about 1.5 minutes. I can move the mouse around, but no clicks or keystrokes register until the end of the wait. Oh, and I don't get my bookmark. I can make them using the "Bookmark This Page" menu item.
I get a similar freeze when I attempt to drag a link from a webpage into a text editor or other application.