Thanx for your replys guys. Well like i said i have a Cisco - Linkys Router. I don't have any idividual switch cuase the router it self have 4 ports for ethernet connections. I have one Desktop (wired Connection direclty from the router, Automatic Ip's work fine)
and 2 laptops connected with wireless. No 1 laptop also toshiba is accepting automatic ip's dhcp and dns work fine. No 2 Laptop that has the problem can not get automatic ip's . Only with mannually ips works fine. I don't have any Internet Security Application Installed. I have already reset the router 2 times, but nothing. So i guess since the other 2 systems ( a desktop and a laptop) work fine with automatic Ip's something is going on to this specific laptop. Now if i am gonna connect the laptop wired and no wireless doesn't have any problem getting automatic ip's.