This seems to indicate that this AP is losing its connectivity to the controller. You first see the b/g and a radios "going down" (as the AP is not responding anymore), then the controller removes the AP from its database (Ap disassociated).
I would check AP connectivity to the controller, and look at the time when this issue is reported. If it repeats (AP drops then comes back, then drops again, etc) the alarm is reported with very recent time, and several occurrences.
From the controller to which this AP is supposed to connect, you may also get some information from Management > logs...
From the controller CLI, you can try debug lwapp errors enable to see what problem the controller reports for this AP.
You can also console to the AP and check what the AP itself is reporting...
hth
Jerome