Driver Problem

I just a freshly built PC with Win7 pro on it. I installed the arduino software, and when I plug in a Nano, it detects it and tries to install a driver but fails. It says "searching online for driver" for a long time then says it fails. On device manager I get Other devices -> USB2.0-Serial. but no com port

Any thoughts on what went wrong? I even uninstalled arduino and reinstalled as admin, same thing. Any help will be appreciated. Oh yeah, I have installed arduino on 3 or 4 other PCs without issue.

The Nano use an FTDI-brand chip for USB-to-Serial. You need to install FTDI drivers. They should be somewhere in the Arduino install or you can download them from the manufacturer:

http://www.ftdichip.com/Drivers/VCP.htm