While using cable from router there appears to be no problem. As soon as the wireless is activated, the system drops out of the internet connection supplied by cable broadband (dedicated internet cable.only when the reouter is reset (which turns off the wireless) is the problem rectified. How can this be recified to allow wireless connection

How did you figure out, that the broadband connection is dropped while wireless is switched on? If you're using one pc or laptop, to check the connection, keep in mind, that if you will use wireless instead of wired connection, you have to deactivate the wired network card. Otherwise, you get 2 ip addresses out of the same range, e.g. 192.168.0.x and both network cards gets the routers address as the default gateway. But which card is used to connect to the internet? You'll never know. Also 2 network cards in the same ip range makes no sense and I've never seen, that it's working.

The set up is: The modem from the internet supplier feeds the router which feeds 3 comps. & a switch which supplies 2 further comps.There are 5 computers on the LAN at the same time. When wireless function was activated, all the computers lost internet connection although 4 were connected by cable. The ethernet cable to the laptop was disconnected prior to booting the laptop. It was suggested by others that possibly there was interference from other local networks; the router interpreted these networks as a threat and "strengthened the firewall" therefore interrupting the connection to the internet. Other suggested to change the chanel but I do not know how to do this. Is there anything that can be done to allow wire connection as the cable outlets are in inconvenient places?

In general, the wired connected computers do have internet access, no matter whether wireless option on the router is enabled or not. If the routers firewall gets under heavy stress, all traffic might be dropped. This could happen, if one of the connected computers has a corrupt network card, that jabbers or, if a connected computer is infected by a virus and therefore causes heavy traffic through the internal and external (internet) network. Btw.: It's always a good idea, to use a channel for wireless network, that does not exist in the direct environment. E.g.: If there is another wireless network using channel 1, you should use a channel number 1+5, so channel 6. If there is a wireless network on channel 6, use channel 1 or 11.

Thankyou . I will try the computers from the newest to the oldest to see if any one computer will cause the disruption. How do I change the chanel on the linksys wireless router?

Oh, depends on the Linksys model. You have to check the manual for that. It should be located, where you configure the AP (access point). Normally there you can choose, which channel should be used.