I have the following problem: when I open web pages in FireFox or Internet Explorer sometimes I get a "server not found" error, then I click "try again" once or twice and it works again. This happens quite often so I don't think the problem is caused by the web site servers, and it happens on many web sites. However does not happen on all sites, It seems I don't have this problem with pages located in the Netherlands (where I'm located too). I checked with someone who has the ISP as I do, if he also had the problem, but that is not the case.
The situation is as followes: I have a Windows XP SP2 computer and a laptop running WinXP SP2, both are connected to a cable Internet connection with a Draytek Vigor 2200 router. Both have the problem. The problem seems to be browser independed as it happens in Firefox and Internet Explorer.
I tried to set the IP address of the DNS server (before it was the routers ip) to be forwarded to the computers connected to the router. I tried both my ISP DNS server and a public DNS server, neither of them fixed the problem.