You may try these steps: click Start, click All Programs, goto Accessories, select Command Prompt, right click on the Command prompt Run as Administrator, Type "ipconfig /flushdns", Hit Enter.
Check if it helps.
You can also try typing:
ipconfig /release
ipconfig /renew
net stop dnscache
net start dnscache
netsh int ip reset resetlog.txt
netsh winsock reset catalog
You can read more here.