Router bugged??

Hello,
hi guys, i got a problem , i try to conect to the internet , to mention that i have a desktop and two laptops, the conections seems to be on but when i try to open a page it doesn`t work , i rebout the router and the web is opening only for 5 min max then is closing again and i must to rebout the router every 5 min to have 5 min interenet, i bought a new router and has the same problem. I called the guys from the network and they said that i have internet conection and they can not help. To mention as well that one of my laptops had a virus and i reinstal the windows but acording to someone i still have viruses in it , the interenet started to make problems only since i tryied to conect this laptop.Whats the deal ?? dont know what else to do !!:(( in some stage when i try to open the web page some message with a big I is coming saying Prokiller and some numbers. And funny is that the yahoo messanger is working , well without being able to call but to write. Please help !!!!!!