Shilelagh

Hello I have a Thomson TG585 v7 (I think) Router and my computer has windows 7 Home premium and is good (ie will not lagg its a gaming computer). When I connect our old router, the thomson, the main computer upstairs next to it works but as soon as I plug in the wired internet to my computer in my room it just says internet cable unplugged. I havnt tried a new cable because the cable was working perfectly fine yesterday when I was using the new router. I have gained wireless access but I really need wired internet. Thanks Also I would like to mention that I was just looking at the connection in the control panel and it flicks on and says enabled for about a second then says network cable unplugged again it said this a couple of times.