Please help me to fix the problem

Hello,
i have dell n4010 laptop.
USING : WIN7,home premium ,

PROBLEM DESCRIPTION:When I turn on my laptop each morning I get a
red "X" beside the WiFi icon and cannot connect to the internet until restart the network device (router). after the restarting the network device (router) it connect but disconnect again within a minute .........

when all other laptop are disconnected which are connected with same router than my laptop connect to the the router when any other laptop get on and connect to the router then may connection get disconnected automatically ..."THIS PROBLEM IS ONLY WITH MY LAPTOP NOT OTHER WHICH ARE CONNECTED WITH THAT ROUTER "


WHAT HAS BEEN TRIED SO FAR WITH NO EFFECT:
1: complete reinstallation of operating system ,
2: re installation of driver
3: Disconnect and re-connect to WiFi.
4: Uninstalled the WLAN card driver and re-installed the latest driver
5: remove network than add again it .


plz give me right solution ....