I am now using quantal with $ uname -a Linux GT683R 3.5.0-15-generic #22-Ubuntu SMP Wed Sep 19 20:01:43 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux and the bug is gone.
I am now using quantal with
$ uname -a
Linux GT683R 3.5.0-15-generic #22-Ubuntu SMP Wed Sep 19 20:01:43 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
and the bug is gone.