iceweasel 4 process not closing on exit

[L V Gandhi]

When ever I close iceweasel 4 in squeeze, process is not closing.
Hence if I restart iceweasel, it says process is running, first close
running process.
I saw from ps -ax as follows
2111 ?        Rl     1:41 /usr/lib/iceweasel/firefox-bin --sm-config-prefix
/firefox-bin-c5rQTp/ --sm-client-id 10cddfd6
How to solve it ie to get the process closed when program is exited from its
file menu or window is closed?
-- 
L V Gandhi