I bought a N900 second hand.Before I had been using Nokia symbian 60 N series and I always wished for something powerful.picked a N900 for Rs.6000/- but,from day 1 there are few issues..
vanilla flashing struck at 20%, phone is slow, lock code option in settings<device lock, not working with nokia code 12345, few files are shown broken.
Im very new to linux and N900, but after reading maemo.org, came to know that flashing is a solution...I tried infinite times to flash vanilla and combined images...combined file flashes fully, be it global, indian,2011 update,etc....but vanilla gets struck at 20%..
I discussed a lot and got good help from kind members like @elros34 , @Mitrigol , @Alecsandru in the thread http://talk.maemo.org/showthread.php?t=89077&page=5
....
rescue OS was also done successfully...after that i tried to flash vanilla normally,but at 20% it is struck...i think the phone is in R&D mode as while booting it is showing settings symbol near NOKIA logo and product information is given in green letters...

copied from terminal when vanilla was flashed...

C:\Program Files\maemo\flasher-3.5>flasher-3.5.exe -F emmc.bin -f
flasher v2.5.2 (Sep 24 2009)

Image 'mmc', size 255947 kB
Version RX-51_2009SE_10.2010.13-2.VANILLA
Suitable USB device not found, waiting.
USB device found found at bus bus-0, device address \\.\libusb0-0001--0x0421-0x0
105.
Found device RX-51, hardware revision 2204
NOLO version 1.4.14
Version of 'sw-release': RX-51_2009SE_20.2010.36-2_PR_MR0
Booting device into flash mode.
Suitable USB device not found, waiting.
USB device found found at bus bus-0, device address \\.\libusb0-0001--0x0421-0x0
1c8.
Raw data transfer EP found at EP2.
[init 20 % 22528 / 255947 kB 8205 kB/s]
C:\Program Files\maemo\flasher-3.5>

i tried on Win XP Service Pack 3 32 bit and Win 7 amd 32 bit
but results are same....can anyone please help me out and remember I'm a newbie...thanks....

i told-you
another pc /os
maybe a laptop with a fresh install of os

so now on 3rd PC...ok ..got dad's laptop...hp pavilion g6...Win 7 home basic..64 bit...

what to do next?please think ...what all i did yesterday and the problems ....
phone's current status-
yesterday after rescue OS, and combined file flash....the problems were there...hence i tried to flash emmc....struck at 20%...and when switched on, it is in R&D mode with green letters and once booted MISSING IMAGES...because i tried only emmc till 20%.....if i flash combined,phone will work ....but slow, no lock code, etc...

Flash Rootfs, then eMMC and then Rootfs again.
Rootfs is also called combined.

Also you shouldn't flash with 64-bit win7, use 32 bit. Even better would be to use linux as it fails somehow less with flashing. You can use virtualBox or VmWare player for it.

Good luck

i tried all combinations....emm and rootfs..... whatever ..emmc struck at 20%...
@Alexsandru told to try on different PC.....laptop is 64 bit....i cant find a 32 bit machine else....
got 1 desktop 32 bit and tried yesterday but in vain...

* Sigh *

Dude. It's not that bloody complicated, but at least 2 ingredients are needed here if you want to cook:

1. Effort
2. The use of your brains.

Let's start with 1.

If you don't understand the process of flashing, why don't you educate yourself, use number 2. and start using google, reading the wiki, etc.

Your questions have been answered only a thousand times, max.

http://wiki.maemo.org/Updating_the_firmware

The use of 64bit Windows has been discussed all over the place as well.
It can easily be avoided by using a linux flavored LiveCD.

Read up here.

https://help.ubuntu.com/community/LiveCD

maybe your vanilla image is broken?

@anthonie sir, you dont know how hard and how many ways i tried out...i agree im new, but of course im putting enough effort for this...followed as per wiki, you know...
now i didnt try in linux for sure but i have ubuntu in my usb stick...
but do know that, i tried flashing in 2 PCs....emmc stops at 20 %....still do you think windows can give trouble?
if you are sure shall i try with ubuntu?need help though...

i got 4 vanilla and 6 combined images....no chance of all broken...rare possibility...yesterday as i said few members tried their best to sort this out but in vain....

If you followed the wiki correctly you would have known the trouble with 64bit Windows, and you would have known which image to use by now. And also you would have bumped into a phrase "md5 checksum".

Well. Start with doing a md5 checksum because right now you are only speculating. You don't know if these images are correct or not.

http://www.winmd5.com/

You don't know what a checksum is?

Look here:
http://en.wikipedia.org/wiki/MD5

For each image that you can download, an Md5 checksum is provided on site. If, after downloading those two don't match, your download is corrupted and useless.

Check the wiki for the exact name of the latest image, needed for your region (if you need or plan to use something differen than global). Use the latest one.

All in all: Take your time. Read up and make sure you understand what you are doing. If you don't understand something or a concept you run into, read up on it first.

This is not a procedure to be "trying" things. You need some knowledge and it's out there.

Good luck

Edit: Oh. And there is no shame in being new to anything. Quite the opposite!