External hard reset watchdog

hey does anyone have any ideas on what would cause and error that cause a 5.7 ap to reboot about every hour and it gives this error

00:38:11 UT : 01/21/01 : File root.c : Line 941 System Startup
00:38:11 UT : 01/21/01 : File root.c : Line 946 Software Version : CANOPY 7.3.6 Oct 24 2005 12:06:56 AP-DES
00:38:11 UT : 01/21/01 : File root.c : Line 950 Software Boot Version : CANOPYBOOT 3.0
00:38:11 UT : 01/21/01 : File root.c : Line 956 FPGA Version : 020205
00:38:11 UT : 01/21/01 : File root.c : Line 960 FPGA Features : DES
00:38:22 UT : 01/21/01 : File C:/ISIPPC/pssppc.250/bsps/devices/whisp/rf.c : Line 2343 Acquired GPS Sync Pulse.
01:30:15 UT : 01/21/01 : File C:/ISIPPC/pssppc.250/bsps/devices/whisp/syslog.c : Line 1062 Time set
01:30:15 UT : 01/21/01 : File C:/ISIPPC/pssppc.250/bsps/devices/whisp/syslog.c : Line 918 System Reset Exception – External Hard Reset WatchDog