Hi, this is an ongoing problem I have had and I'm all out of ideas

I use a Netgear router, with two XP Computers hardwired via Ethernet.
My internet provider is Tiscali and for just over a month now I have been losing my internet connection, but the router stays connected, MSN messenger etc.. Sign out, the internet won't work, and within a minute it will be back again, but the router says its connected all the time. I know for a fact its not my PC because both of the computers attached to the router do it...

Also I have taken my router back to factory default and even tried the old USB router, which also looses connection.

My telephones are wired as they should be, It was all fine and all of a sudden this happened... I didn't change anything to cause it to happen. Filters are attached and I have tried a new one... to no avail and there is nothing I can think of causing interference.

I have contacted Tiscali and they have done a line test which confirms my lines are fine??

Its driving me nuts so any help would be much appreciated.

You could try to set the mtu size differently, usually a DSL Modem/Router has a standard setting of 1492. Try reducing it to a number between 1400 and 1492 and see what happens.
My first instinct was to trash on the router but since you said you tried a different one and the same thing happened so that can't be it. My second thought was networks card in your computer but that on both PC the network cards won't prob. Work is unlikely. You also said that comunication between the 2 computers is fine, maybe try to make a large file transfer if something is wrong you might not detect it by just moving a small file. If you worried about interference you can allways by shielded cables but I don't think that's the problem, I run a 300 feet cable next to powercables and satellite cables and have no problem at all. Try changing the MTU Setting and maybe ask your provider if they did changes on their server or if some line upgrading is going on in your area.

You have two computers yes? If you do not set them each at a different IP address or let the router auto config, the conflict will cause intermitent internet.
A standard router will mask the real ip with 192.168.1.1. You will then have each of your computers configured to 192.168.1.100 and 192.168.1.101 But if those two numbers are not different, the router gets confused and tries to connect both and it will. However the problem will cause information collitions at which point the router tries to supply internet access to both computers, and it can't resulting in data loss. So the computer keeps trying to connect and the router keeps disconnecting you.
If running xp, double click the network icon in the task bar, click the support tab, and check that the IP Address is not the same as what is on the other computer.
'IT guy'