Well the strange thing is that I have TOTALLY different system here (Hardware and Software) and that both have exactly the same issue with the N900 only. I flashed already other devices like the N95 on the XP machine before without any problems.

I really begin to loose the trust towards Nokia with all that trouble, its the third time that I have to flash my N900 (Before software like Joikuspot bricked my N900). That is the reason why my nerves are getting killed currently.

Edit: Is it really required to add "-R" add the end of the 2nd command? Just a thought.