I had the same kinda thing...

Memory card not found yet PC can read it...

I have done almost all things... which on net...

Last resort: Flashed my n900


1. Downloaded (http://tablets-dev.nokia.com/nokia_N900.php)
• flasher-3.5.exe
(http://tablets-dev.nokia.com/maemo-d....5_2.5.2.2.exe)
• RX-51_2009SE_10.2010.19-1_PR_COMBINED_MR0_ARM.bin
(http://tablets-dev.nokia.com/nokia_N...ED_MR0_ARM.bin)
• RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin
(http://tablets-dev.nokia.com/nokia_N...MC_MR0_ARM.bin)

2. I installed the "flasher-3.5.exe"
3. I then moved
"RX-51_2009SE_10.2010.19-1_PR_COMBINED_MR0_ARM.bin"
"RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin"
To the directory where I installed the flasher (Default is C:\Program Files\maemo\flasher-3.5).
4. I then done a full backup of my N900 using the backup tool on the phone and moved all my stuff on to the memory card.
5. Ensure the battery is at least half full.
6. Unplug charger cable and switch off the device.
7. Open the Command Prompt (Start then Run or Windows Logo key + R) and type "cmd" then press Enter (this will open a black window).
8. Change the directory to the Flasher's path by typing in "cd "%ProgramFiles%\maemo\flasher-3.5"
9. Hold the u key on the device keyboard and connect the USB cable at the same time.
10. Run the following command by typing:
"flasher-3.5.exe -F RX-51_2009SE_10.2010.19-1_PR_COMBINED_MR0_ARM.bin -f"

After this completes

11. Run the following command by typing:
"flasher-3.5.exe -F RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin -f -R"

The flash will take around 1 minute after which the device will reboot.
The bright Nokia screen will come up on the screen with the USB icon on the top right followed by progression dots with yellow LED blinking for a few seconds
And you’re done. Welcome to the world on 1.2

Next now nokia can saw an corrupted memory card.

Then format it with nokia inbuilt formatting process.

thats it.. working fine now..