nevermind, bought Arduino Nano 3.0 and everything works fine again.
Maybe there is a simple solution:
You should select "Processor: Atmega328P (Old Bootloader" in the Tools menu.
This is necessary for near all (older) NANO boards.
I switched to Arduino IDE v1.5.6-r2 because found somewhere this may fix my problem but it doesn't.
Settings i am using:
Board: Arduino NANO
Processor: ATmega328
Programmer: AVRISP mkII