Hi,
I have a new laptop and only usb-3 port and cant install the serial drivers
are the drivers only for usb-2 ???????
//Hasse :o
Try putting a usb2 hub between the usb3 and the Arduino - some usb3 ports act weird. I have a computer where mice and keyboards don't work on usb3 ports...
Also, are you using a clone? Many of the congress use different serial chips, hence different drivers. Look at the chip near the usb connector - it will probably be a 16u2 (use official drivers), ch340g (get the drivers for that, ch341ser.exe - installer looks super sketchy, lots of engrish, but works fine), or ft232 (ftdi - driver comes with Arduino - but some of these are counterfeit and get bricked when you plug them into a Windows system with some versions of the ftdi diver, which were distributed via Windows update, there's lots of info on this arguing the web)
Thanks for the tip, have tried everything, but it refuses to install drivers for serial
May connect the second computer so long until it appears a solution to the problem
Thanks anyway 
Must have been written on the drivers I've tried
But now I found the correct drivers that works in all cases 
http://www.microcontrols.org/arduino-uno-clone-ch340-ch341-chipset-usb-drivers/
that driver works lika a charm