Firefox 4 strange dialogs

[Alex]

On Sun, May 1, 2011 at 2:09 PM, Jim Byrnes <jf_byrnes at comcast.net> wrote:
> Using Firefox 4.0.1 on Ubuntu 10.04. I'm seeing dialog boxes that have no
> title bar and no icon next to the text displayed.  All I see is the border
> of the dialog with a grey background, the text message and any OK,Cancel etc
> buttons.  This seems to happen with modal dialogs but non-modal ones seem to
> display as expected.
>
> An example would be the dialog Yahoo mail pops up when you delete the last
> message from the spam folder.
>
> Is anyone else seeing this and know of a fix?
>
> Regards,  Jim

Like this? http://puu.sh/1Qd3

That's how those dialogs are supposed to look in Firefox 4.