Arp Virus

We can not browse the web normally, it will pop up a window to show "The Earn the QQ...". The web page has beed embeded a link to another website. I have check it and found there mighe be Arp virus. use arp -a and found gateway MAC address is floating. Download the tools to scan whole company computer, and found our sale's computer MAC address match the result. Asked sale man disconect lan. And we can browse the web OK.