i have 2 laptops witch are connected by wireles connection to each other,i have a cable modem connected to a wireless router ok, but when i try to enter wep key they disconnect............thanks

Of course it does; that is what it is supposed to do. You'll need to enter the wep key first on the router (causing the disconnect), and then on your laptop, when hopefully it will connect again.

Things will work more smootly in getting your security set up if you connect one of your computers via a wired connection while getting the security set up on your router. That way, the machine you are using to set up the router won't disconnect as soon as you enable security.