Munir,
When troubleshooting a broadcast storm, I like to use the "show l2stats" command. This will display the number of packets that have gone to the CPU on a per vlan basis. Before running the command, I will issue a "clear counters" command and then "show l2stats" at a known time (4-5 seconds or so). This way I can determine about how many packets per second have gone to the CPU and can determine which vlans are high or not. If there is a standout vlan, I will then use ELRP in order to find out which ports are looped. Hope this helps.
Brad