My router RB2011L connects and disconnects

Hi,
I have a big problem of my router mikroktik RB 2011L.
It connects and disconnects automatically after every 2 minutes.
I have upgraded it but nothing changes.
Its current version of routerOS is 5.25 mipsbe.
Regards…

If it is periodical, every two minutes, it must be a watchdog or netwatch rule that is doing it.

or it can be http://forum.mikrotik.com/t/new-ethernet-port-flap-issue-enquiery-pls-join/49200/1