I work fine with Arduino Uno, but no Upload with Nano

Hi folks, I am an Arduino beginner and my question is:

I am using Windows 7 64Bit and chinese Arduino Hardware. After installing the CH341 USB serial Driver directly from the chinese site, I am working fine with the Arduino Uno, I've installed several shields and modified the SW, all working fine !

But with my Nano I cannot upload ! The error message is: "error opening serial port COM 10 (port busy)"

I select the proper Hardware and the same COM Port in "Tools"
I try different USB cables
I try 5 different Nano HW
Nano Boards use the same HW as the Uno (Mega328P and serial Chip CH340G, the only difference is the subnumber on the 328P is in Uno "AU1519"- working and in NAno "AU 1532" - not working)
Nano has Auto Bootloader (green LED is blinking)

Has anyone an idea ?
Thank in advance, friendly greatings from Austria in Europe

Try restarting your computer. Sometimes a glitch will cause a port to get stuck in an unusable state and a restart will fix that.

dear helmut-2,
to Solve this problem you must:

1.right click on (My Computer) window.
2.Click Properties
3.click "device Manager" on the left side
4.click twice on "Ports (COM & LPT)"
5.right click on "Arduino"
6.click "update driver software"
7.click the second option"browsing
8.choose the drivers folder in Arduino folder (in Program files folder)
9.click "next"
IN ARDUINO IDE:
1.click "tools" tab
2.choose the board type
3.choose the Arduino COM

Regards

,kiroloes

Thanks for your answers. I found the solution: I had to choose "arduino nano" and processor ATmega 328P (Old bootloader) and now it works !