[c-nsp] BPDU Guard issue

[Stanly Johns]

Hi,
Is it possible for a BPDU guard enabled switch port to get disabled without
connecting any other device than the IP Phone and a PC ? I had to do a shut
and no shut to bring it up !
The logs are as follows. your inputs are highly appreciated.

Nov  2 04:13:02.388: %VQPCLIENT-7-RECONF: Reconfirming VMPS responses
Nov  2 04:19:15.286: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port
FastEthernet0/21 with BPDU Guard enabled. Disabling port.
Nov  2 04:19:15.286: %PM-4-ERR_DISABLE: bpduguard error detected on Fa0/21,
putting Fa0/21 in err-disable state
Nov  2 04:19:16.334: %LINEPROTO-5-UPDOWN: Line protocol on Interface
FastEthernet0/21, changed state to down
Nov  2 04:19:17.332: %LINK-3-UPDOWN: Interface FastEthernet0/21, changed
state to down
Nov  2 04:43:59.058: %SYS-5-CONFIG_I: Configured from console by XXX on vty0
(X.X.X.X.)
Nov  2 05:09:57.162: %LINK-5-CHANGED: Interface FastEthernet0/21, changed
state to administratively down
Nov  2 05:10:03.193: %LINK-3-UPDOWN: Interface FastEthernet0/21, changed
state to down
Nov  2 05:10:03.327: %ILPOWER-7-DETECT: Interface Fa0/21: Power Device
detected: Cisco PD
Nov  2 05:10:07.446: %LINK-3-UPDOWN: Interface FastEthernet0/21, changed
state to up
Nov  2 05:10:08.453: %LINEPROTO-5-UPDOWN: Line protocol on Interface
FastEthernet0/21, changed state to up

3560#sh runn int f0/21
Building configuration...
Current configuration : 187 bytes
!
interface FastEthernet0/21
 switchport access vlan dynamic
 switchport mode access
 switchport voice vlan 440
 no mdix auto
 spanning-tree portfast
 spanning-tree bpduguard enable
3560#sh cdp nei f0/21 det
-------------------------
Device ID: SEP0012802908E5
Entry address(es):
  IP address: X.X.X.X
Platform: Cisco IP Phone 7960,  Capabilities: Host Phone
Interface: FastEthernet0/21,  Port ID (outgoing port): Port 1
Holdtime : 166 sec
Version :
P00308000900
advertisement version: 2
Duplex: full
Power drawn: 6.300 Watts
Management address(es):