Internet dropping on one computer

I'm having some problems with my network but the problems only appear on one device hooked up to the network.

I have a Belkin router with one laptop, two desktops connected to it. As well as that, I have my Xbox 360 wired into the same computer I'm having problems with.

It's only the one computer that does this and when I say the internet connection drops, well, it isn't quite that straight forward. Downloads will still continue but I can't browse. This happens everyday throughout the day and it will stop my browsing for a few minutes and then suddenly let me again with seemingly no reason. My network connection isn't dropping, I just can't browse. All at the same time, my Xbox 360 can be connected with no problems and doesn't drop it's connection when this happens.

It's got me totally confused, any help at all would be great.

Thanks.

Is the affected computer powered by the same electrical point as the router and do you also have a fairly new television set in hte same power point? I ask only because I'm working on a customer's system where a Panasonic TV affects ADSL to the point of cutting it off completely. When I turn the screen off using its burn protection facility, ADSL comes back on.

When I separate the two appliances to different power outlets, ADSL remains on but with greatly reduced speed. Research continues but I'd like to know if you have a similar setup.

There is a TV plugged in the same wall socket but it's not new and has been plugged in for a good while now. I have just got a new TV upstairs (well, an old one but only recently set up) - not sure if that's anything to do with it. I'll check it out more when I get chance.

May sound dumb but how do I try another port on the router?

I have my Xbox 360 on the network - it's wired into the same computer I'm having problems with and I'm sharing the internet connection from the wireless network through that computer.

From Post #1 "I have a Belkin router"

Apologies for the late reply, been away and now having some other computer issues!

The Xbox is wired into the desktop computer with an ethernet cable - the desktop connects to the network wirelessly. The internet connection that the desktop uses is shared with the wired connection to the xbox.

Thanks for the help so far.