OK, now I see what you mean. I have that as well on both Firefox and Thunderbird. I do have Aero on, so it actually helps to see the text. This is probably by design. I don't know of a way of removing it, but there might be a userChrome edit that you could use. Post over in Firefox Support at Index page • mozillaZine Forums and one of the experts in modding Firefox can probably help you remove it.
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