Network Loop Finding Process

Hi,

In My Company Setup I am facing some Firewall related issues;when this firewall connected in Network switch My plant to plant communication Goes down;This problem occurs in the evening only... !

Network Setup is like below; We Have 3 Plants and those all are connected Through Wireless as Point to Point; Every Plant has 2 Devices. Plant A, Plant B, Plant C Plant A Wireless Device1 has a same SSID like Plant B Device1(its connected Plant A >>>>>>>>> Plant B) Plant B Device2 is Connected to Plant C Device1 (with same SSID) For Redundancy we configured Extra Devices Of Plant A and Plant C its is in the Switch But SSID are different than Exist. Firewall Nsa2400 is Installed at both Plants at Plant A and Plant B only.

Through I am getting few CDP check sum errors.. is this a cause of the problem... or how to use this tool to find a loop

Regards, Swapz123