IP Phones rebooting and not powering up

Hi -

I cannot get my procurve 2910al switch to keep delivering power to our phones.  They power up for about 1 second, and then reboot.  I keep getting this error in the procurve switch log:

PD Over Current indication

There is plenty of power available.

Running this version of firmware code W.15.08.0012 and here is how much power is available:

sho power

 Status and Counters - System Power Status


  Pre-standard Detect : On
  Operational Status  : On    
  Usage Threshold (%) : 80

 Chassis power-over-ethernet:

  Total Available Power  :  382 W
  Total Failover Power   :    0 W
  Total used Power       :   34 W +/- 6W      
  Total Remaining Power  :  348 W              


 Internal Power
        1   382W/POE+ /Connected.                      
 External Power
        EPS1   /Not Connected.

Any advice is greatly appreciated!

Thanks!