When making DNS changes it can often take a while for various DNS caches between yourself and the source to clear. I’ve often found that the last ones to change are the ones in the last few metres – from your router to your browser.
You’ll need to find the one upstream that’s incorrect and fix “backwards” from that – i.e. check your Windows DNS cache first, then work towards the browser.
According to OpenDNS, all browsers will clear their DNS cache if you use their clear cache functionality, but that’ll take out a lot more than DNS.
Chrome: Visit chrome://net-internals/#
Firefox: Close and re-open browser should do it – otherwise there’s a fiddly method involving about:config. When I’ve tried out the plug-ins I’ll add a suggestion, but if you’ve using one let me know in the comments and I’ll update this.
IE: no independent DNS cache.
Local Windows machine
At command prompt: ipconfig /flushdns
Use ping to see if you’re resolving OK.
Windows Server (if acting as DNS cache)
At command prompt: dnscommand <servername> /clearcache