The problem which I am currently having is quite confusing and bizarre, but ill do my best to explain it in the simplest terms.

Recently, my internet speed had been becoming increasingly slow, getting to a point where web pages just refuse to load up. I initially blamed this problem on my ISP. However it occurred to me yesterday that the my internet speed only becomes slow when one laptop is turned on. When this laptop is turned on the speed of the internet drops to around 0.04MBPS, but when it is turned off the speed of the internet shoots up again. However more bizzarely the internet is slow when the laptop is on but when the WLAN is off and even when the laptop is disconnected from the network entirely. It only happens with this laptop (which is running Windows Vista) and other laptops, tablets, games consoles, smartphones etc. that are using the same router to connect to the internet all work fine and dont pull the internet connection down. I was wondering what could I possibly do to make the computer not drag the internet down, as this does seem to be the source of the internet becoming incredibly slow. I have run a full system virus scan, which has shown nothing. Any help will be greatly appreciated Thanks, Jay