What's the problem of flash

hi,everyone.

I confront the problem that: the flash can work sometimes.

The flash is AM29LV641DH-90

When I use flashprogrammer flashdown elf,it can flash down sometimes like :

--------------------------------# ! /bin/sh# # This file was automatically generated by the Nios II IDE Flash Programmer.# # It will be overwritten when the flash programmer options change.#

cd I:/WOEPCS/hello_world_0/Debug

# Creating .flash file for the FPGA configuration

$SOPC_KIT_NIOS2/bin/sof2flash --epcs --input=I:/WOEPCS/WOEPCS.sof --output=WOEPC

S.flash

Info: *******************************************************************

Info: Running Quartus II Convert_programming_file

Info: Command: quartus_cpf --no_banner --convert --device=EPCS64 --option=WOEPCS

.opt I:/WOEPCS/WOEPCS.sof WOEPCS.pof

Info: Quartus II Convert_programming_file was successful. 0 errors, 0 warnings

Info: Processing ended: Mon Oct 23 19:40:15 2006

Info: Elapsed time: 00:00:02

Info: *******************************************************************

Info: Running Quartus II Convert_programming_file

Info: Command: quartus_cpf --no_banner --convert WOEPCS.pof WOEPCS.rpd

Info: Quartus II Convert_programming_file was successful. 0 errors, 0 warnings

Info: Processing ended: Mon Oct 23 19:40:17 2006

Info: Elapsed time: 00:00:01

# Programming flash with the FPGA configuration

$SOPC_KIT_NIOS2/bin/nios2-flash-programmer --cable='ByteBlasterMV [LPT1]' --devi

ce=1 --epcs --base=0x00000000 WOEPCS.flash

Using cable "ByteBlasterMV [LPT1]", device 1, instance 0x00

Resetting and pausing target processor: OK

: Checksumming existing contents

00000000 : Verifying existing contents

00008000 : Verifying existing contents

00010000 : Verifying existing contents

00000000 : Reading existing contents

00008000 : Reading existing contents

00010000 : Reading existing contents

Checksummed/read 96kB in 6.6s

00000000 ( 0%): Erasing

00008000 (33%): Erasing

00010000 (66%): Erasing

Erased 96kB in 2.8s (34.2kB/s)

00000000 ( 0%): Programming

00008000 (33%): Programming

00010000 (66%): Programming

Programmed 76KB +20KB in 3.9s (24.6KB/s)

Did not attempt to verify device contents

Leaving target processor paused

# Creating .flash file for the project

$SOPC_KIT_NIOS2/bin/elf2flash --base=0x00800000 --end=0xbfffff --reset=0x0 --inp

ut=hello_world_0.elf --output=cfi_flash_0.flash --boot=$SOPC_KIT_NIOS2/component

s/altera_nios2/boot_loader_cfi.srec

# Programming flash with the project

$SOPC_KIT_NIOS2/bin/nios2-flash-programmer --cable='ByteBlasterMV [LPT1]' --devi

ce=1 --base=0x00800000 cfi_flash_0.flash

Using cable "ByteBlasterMV [LPT1]", device 1, instance 0x00

Resetting and pausing target processor: OK

: Checksumming existing contents

00000000 : Reading existing contents

Checksummed/read 16kB in 1.1s

00000000 ( 0%): Erasing

Erased 64kB in 0.3s (213.3kB/s)

00000000 ( 0%): Programming

Programmed 49KB +15KB in 3.5s (18.2KB/s)

Device contents checksummed OK

Leaving target processor paused

--------------------------------------------------------

But sometimes(and almost) ,it appear like this:

NO CFI Table found at 0x800000

----------------------------------------------------

The step I create my board description is that:I use protel 2004 to generate wirelist formate file.then In the SOPC new description,.........

How can I know whether the flash is OK or NOT.Is flash easy to broke.

Could anyone give me some advice to findout where is wrong.Thanks.

Best wishes!