I was trying to execute the " Blink led" program. I did it successfully in the workshop on 18th January. But when I am trying to do on my laptop,after successful compilation, when I tried to upload, it is giving 'serial port not selected' error. The OS in my laptop is windows 7 professional. To solve this problem, I tried to select a serial port from Tool menu. I found out that serial port selection was greyed out. I reinstalled the arduino software by selecting all drivers as was told in the additional reading material. But still the port is greyed out I have gone through arduino forums to solve the problem. They are suggesting to install the USB driver through arduino software. But I am not seeing the arduino downloaded software in the browsing option of the 'update driver' option in the device driver.