Site not found probably indicates a DNS error.
I don't know what the windows equivalent is - but in linux/osx you should be able to run a command called nslookup from the command line:
[mpeters@athens ~]$ nslookup
www.cornsnakesource.com
Server: 127.0.0.1
Address: 127.0.0.1#53
Non-authoritative answer:
www.cornsnakesource.com canonical name = cornsnakesource.com.
Name: cornsnakesource.com
Address: 65.99.253.59
-=-
I'm sure there is a windows equivalent to nslookup you can run from the DOS prompt - I've used it before when troubleshooting why a friends PC could not find my network printer - but I don't remember what it is.
Anyway - if your nameserver can't find it, that's why you can't get to it. If there is an alternate nameserver you can use, try that - otherwise, you may need to submit a support request to your ISP telling them their nameserver needs to rebuild it's cache, as that's probably the problem. If they use bind as their nameserver, they may just need to restart it - I've seen that happen before, bind gets stuck and stops updating its cache. But anyway, I suspect the problem is on their end.
What sometimes happens is a website sets a short life for the name resolution and the nameservers are suppose to check that often, but some ISPs ignore the life and only check for new IP address once a month, resulting in issues if the IP address of the website changed.
I got so fed up with my ISPs nameservers either going down or having bad info that I just run my own now - but that's probably not what you want to do.
