arduino nano: unknown device

by starting the system the arduino nano is not installed correctly. it is marked as "unknown device" in device manager first. only unplugging and attaching the board again helps to install it correctly. i have also tested it on different systems and with differnt arduino nano. all other arduino boards i had until now worked directly by starting the system but not the nano. can anybody confirm this behaviour? is there a workaround?

system: windows7 x64 arduino: nano v3.0

i appreciate your helpful suggestions


greetings and thanks to switzerland – thats it. i identified pin 25 as gnd and soldered 25 (gnd) and 26 (test) together → it runs, the arduino nano always is identified immediately by starting the system. attached the signal description of FTDI FT232RL