I swear I haven't done anything these days but now it is working greatly as before ~~
I am so lucky !!!!

For so many times I have successfully flashed the EMMC and ROOFTS( In other words, the nokia drives in my pc are fully installed). But now it can't be flashed any more ( maybe a hardware problem )whatever I try.

Details:
Yesterday when I pulled out the battery (because My N900 had no response for quite a long time ) to reboot it , then the tragedy occurred .........
What's worse was that for I had installed the Backupmenu-v2 with multiboot already, simply I wanted to rewrite the roofts and opt , however, it failed for twice. I was so lost at that time that I stupidly cleared the opt with the backup's extra function.

So I had no choice but flasher 3.5. Firstly I flashed the EMMC and as described in the title it failed
Then I tried to flashed the ROM and It did work.
Now my N900 can boot again but without the 32G any more and even no enough memory to open a coming SMS( phone functions well )....

I TRY:
When I flash the EMMC(BEFORE FLASH ROOFTS) it says that :
D:\Program Files\maemo\flasher-3.5>flasher-3.5.exe -F 1.bin -f -R
flasher v2.5.2 (Sep 24 2009)

Image 'mmc', size 255947 kB
Version RX-51_2009SE_10.2010.13-2.VANILLA
USB device found found at bus bus-0, device address \\.\libusb0-0001--0x0421-0x0
1c8.
Raw data transfer EP found at EP2.
Using flashing protocol Mk II.
SU_PREPARE_DATA_BLOCK_REQ terminated with error code 3.

( You can treat me as a Noob as you like and show me your opinions).

Raw data transfer EP foundat EP2.
？？？？？

I'm sure this has come up before here. Try googling something like this:

http://www.google.com/search?q=site%...%20code%201%22

Sounds to me like component failure so maybe you have damaged the phone by dropping it ?.

Make sure the device is turned off, run the flasher command, when it says waiting for device, plug the device (still turned off) into the usb port of your computer and wait.

I just pulled out the battery compulsively to reboot it

I just did what you said but it didn't work

So what happened when you browsed through and tried some of the suggestions on the 214 pages that Google came up with?

http://www.google.com/search?q=site%...%20code%201%22

I find some ways to handle it .Though I dont know whether it works or not

please help ...
I tried to reflash the kernel after flash the rom ,but still unable to flash the emmc ,,,,