Unfortunately, you've not given us enough information. After the re-install of the operating system, it's required to reinstall all drivers including the motherboard/chipset drivers and in your case, the network adapter drivers. Did you do this? Did you use the HP recovery option to restore the computer back to factory conditions? This option should re-install all of the drivers but did you do this? And what type of internet connection are you using? Wireless or wired? If using one type, have you tried using the other? Do other browsers access the internet correctly?

Hope this helps and let us know more.