Hi Stieven,
Do you have any Trunks defined ??
I would look into the LACP configuration as this can Block and unblock ports as well.
Also have you set Spanning tree Priorities for the root switch and edge switches.
If you have not set the Root switch to priority 1 and all others to priority 4, I would recommend doing that, also do you have any blade servers as the switches in these can make spanning tree to renegotiate.
I hope this helps.
Jase