Dear All,
I have some problem in ,y bridging network that show in the following pic:
If you want to make transparent network, you may use WDS to establish it,
http://wiki.mikrotik.com/wiki/Wireless_repeater
I'm not aware which interfaces you have bridged.
Enable rstp on MikroTik bridge, it will help you to cooperate with network loop.
Please, check careful bridge configuration.