康佳LED55X5000DE死机

修修就好

康佳LED55X5000DE死机，打印信息如下：
2013-7-29, 22:24:11
COM4, BaudRate:115200 bps, RXD: VGA->12,TXD: VGA->15, Printed by RT809F:
UART_115200
BIST0-OK
[3456789AB]
[56789ABC]-78
_U
Hello U-Boot

U-Boot 1.1.6 (Oct 13 2011 - 14:58:32)

Board: MSTAR AMBER1 (CPU Speed 504 MHz)
DRAM:  256 MBytes
U-Boot is running at DRAM 0x87600000
Module: KEYPAD USB FAT NAND FLASH UBI UBIFS NET SPI STANDBY JFFS2 LOGO OSD ENV=SERIAL
Flash is detected (0x0707, 0xEF, 0x40, 0x14)
MDrv_SERFLASH_GetInfo()
u32AccessWidth = 1
u32TotalSize   = 1048576
u32SecNum      = 16
u32SecSize     = 65536
>>> nand: AUTO CE/WP

Flash Make code = 0xEC, ID = 0xDA

Flash Make code = 0xEC, ID = 0xDA
...
NAND: 256 MBytes
In:    serial
Out:   serial
Err:   serial
Net:   MSVC00B000100100421604TH0000000T
EnvFlag =:128.....CONFIG_ENV_ADDR=:E0000
cbuffer[0] =:0xFF...cbuffer[1] =:0xFF...cbuffer[11] =:0xFF
Check USB port[0]:
Error, couldn't init Lowlevel part
Check USB port[1]:
Error, couldn't init Lowlevel part
keypad_pressed_1 is:0
[0]adc_val =:0xFF
keypad_pressed_2 is:0
--> ac boot <--

UART BUS OFF!

修修就好

请教各位师傅是啥问题？