Hello friends.

This morning I "repaired" a friend's computer. The usb cable was
disconnected (the device was a printer). When I re-connected the
usb cable, the computer needed the driver. I though that the driver
was already installed. Do you need to install a driver every time you
re-connect a usb device? The printer worked before the cable was
disconnected...
Thanks.

Sometimes...

Which version of Windows?

Windows xp.
The printer was working properly (my friend said). Then, the driver
was installed (I supose). Then, you disconnect, and reconnect the usb cable.
And now ¡the driver is not installed!
The printer is hp (I don`t remember model)

What did you repair? If this was a repair installation then the hardware is setup all over again and since the printer was not attached at the time the new installation would know nothing about it and you would get the sequence you described.

Thanks for your answers, Paul and Mjc.