You may want to try to Flush your computer's DNS. Sometimes it helps! Here how you should do it (exact steps for Windows XP - may deffer for Windows 7, 8, etc...):
1. Go to the start menu >> Accessories >> Command Prompt
2. Before flushing your DNS - make sure to check whether you need it! You can do it by simply typing in the Command Prompt: "ipconfig /displaydns" Do not use " AND!! leave a space between "ipconfig" and "/".
3. After checking all the DNS, run the following command in the Command Prompt: "ipconfig /flushdns" - again - do not use the "" symbols + leave a space between "ipconfig" and "/". Hope that will help you resolve the problem!
Paul