FC7 Thunderbird 2.0 missing headers

I don't see headers of message (fromeither in the main window or in
the message window
I could see it in 1.5 and before last updates.

In error console of Thunderbird I see an error at line 69 of chrome viewheaders
   document.getElementById("ViewAllHeaders").setAttribute("label",jViewHeadersGetStr("viewheaders-normal-label"));


Any idea???
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Antonio Montagnani
Skype : antoniomontag