Switch 3com 5800 Series

[Bruno_MCTI]

Hello. I have some 3com 5800 series that I manage at work. This switches began to show port flaps a few days ago. As usual, I checked the layer 1 and 2 for problems but could not see anything other than normal. The flaps continued. Some trap messages are now showing "

 %Jul 11 20:10:10:782 2012 SWBSPS01 L2INF/5/PORT LINK STATUS CHANGE:- 1 -  GigabitEthernet1/0/30 is DOWN    -  

and 

%Jul 11 20:10:13:810 2012 SWBSPS01 L2INF/5/PORT LINK STATUS CHANGE:- 1 -  GigabitEthernet1/0/30 is UP .

this port is connected to a AP 2750 and it is configured as follow:

[SWITCH]display current-configuration interface GigabitEthernet 1/0/30

# interface GigabitEthernet1/0/30  

stp edged-port enable  

port access vlan 11  

apply qos-profile default

I moved it to another port, changed the AP but this error keeps coming.

What else could I do?

Thanks in advance