THX!!! That wasn't clear!!

OK. The full-flash-process in windowsxp is:
1. Install Flasher

2. the inner rootfs flash-drive
http://wiki.maemo.org/Updating_the_t...ndows_7_32-bit

3. then the bigger (which visible with usb)
http://wiki.maemo.org/Updating_the_t...MC_in_the_N900
Only, if it is necessarily. This delete everything from your device, make backup & copy your files to computer.

Sorry about my stupidity!