There are three 2960 took this problem:

WS-C2960-48TC-S 12.2(25)  2

WS-C2960-24TC-S 12.2(25)  1

upgrade from 12.2(25) to 12.2(50)

upload the IOS by TFTP to flash:

boot system flash:****

wr

reload

Failed to get configuration
Invalid parameter block -- no mac address available.
Xmodem file system is available.

The system has been interrupted, or encountered an error
while non-volatile environment variables were being read
out of flash.  If you interrupted the system, it would be
a good idea to issue the reset command now, or the
environment variables may be lost.  The following
commands will initialize the flash filesystem, and finish
loading the operating system software:

    flash_init
    boot

switch: flash_init
Initializing Flash...
...no flash filesystems found.

than i try to type some command:

switch: dir

List of filesystems currently registered:

xmodem[0]: (read-only)
null[1]: (read-write)

switch: flash_init
Initializing Flash...
...no flash filesystems found.

switch:

i try to sent original IOS to null: filesystem and successed, but after reboot nothing happen...

is this a hardware problem? just like flash card get crashed....

any suggestion?

thanks and Best REgards