I can confirm that turning off pango as described above also fixes the issue for me.
My system: Ubuntu Dapper Thunderbird version 1.5.0.7 (20060922) (dapper latest) Linux xxx 2.6.15-27-686 #1 SMP PREEMPT Sat Sep 16 02:13:27 UTC 2006 i686 GNU/Linux -- keyboard navigation in message faulty https://launchpad.net/bugs/38758 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
