I've been trying to help my father-in-law with this problem but haven't been able to get anywhere. Since the weekend the web browsers on his computer (Chrome and Internet Explorer on Windows XP) will only let him get to certain sites - for example, he is able to conduct his online banking but he cannot visit www.bbc.co.uk, www.amazon.co.uk or www.ancestry.com. There is another computer in the house that goes via the same router and this can connect to both, which suggests it is his machine.

I tried running a tracert to www.bbc.co.uk and managed to get through, but the web browser hangs with a message that it is waiting for a response. I tried using the WinSockFix tool in case it was anything to do with a recent registry change but that didn't work either.

He can't think of anything that he recently did on his machine to cause the problem. Can anyone help?