What happened with the Speedtest site, did you get a Ping and Bandwidth result? Have you changed the DNS server settings on your router as suggested by BaggaZee? Wait - are you using a PC/laptop and router, or some other setup? Have you tried going through your router settings and comparing them to what is stipulated by your ISP (proxy server settings, MTU, all that jazz)?
Hmmm, back to basics then, can you test with other devices or switch from wireless to wired? If wireless, try changing channel on your router, try each of 1, 6 & 11 for starters, or if you;re interested, install inSSIDer for Home – Discover The Wi-Fi Around You | MetaGeek & have a look at which frequencies are getting hammered & avoid them.
Funky,are you with Virgin?If you are domiciled in the Rushcliffe area your broadband speed should hve been increased.I was on 30 Meg and it has now been doubled up to 60 Meg free of charge.I would check this out if I were you.
Funky The only thing I can think of which might have contributed to solving my problem was 'resetting my browser'. You can do this without losing any of your bookmarks/favorites.