The port appeared as disabled in the IDE.
Then in System/Device Manager, by plugging and unplugging the Nano board into the USB port, I see that it appears as USB Serial Converter in Unversal bus controllers (well this Windows is in Spanish, I don't remember which is the Ensligh correct).
I made Windows update the driver (Arduino/drivers) folder, and it was updated as USB Serial Bus Controller.
Then it appeared as COM3, but the upload, even the basic skecth, lasts forever.
Tried to upload the driver again, now it appears as disabled again.
Please help!