Thanks for responding
I have spent hours trying to fix this. And I rang the broadband provider (Virgin Media) and they were no use, even though it is their router.
The old router was taken away by the broadband provider, but I think it was a netgear. But I don't have the model number. It was white
the new router is a d-link DIR 615.
My computer is an Dell Inspiron 1525 Laptop.
Another interesting point is that my girlfriend's laptop doesn't have this problem. It can connect to the new router, and she doesn't have this issue with the old wireless network trying to connect as well. My laptop was the one which I used to set up the new router. But hers is the one that works fine.
It is worth noting that this problem started as soon as the new router was set up. I tried to fix it for a few days to no avail. Then it just came right by itself and was fine for 3 or 4 days. Then the problem returned again, and hasn't gone away. I am using the internet now by connecting a cable to the laptop coming out of one of the router ports.
My iphone also has no problems connecting.
Thanks again and appreciate any ideas you may have.