Although the laptop is seen on the network and is assigned an IP address and files can be transferred to and from the main desktop, an internet connection is not formed. Again the laptop is seen on the router's webpage. This is a sudden occurence,  previously there were no problems with exactly the same settings.I've tried both the sopplied wireless card and an external card. Same situation.

 I also have another desktop which does connect to the internet through the router with no problems whether or not the laptop is off or on.

 Suggestions? John