Hi,
You could try flushing DNS with :http://www.bouncegeek.com/how-to-flush-dns/http://www.bouncegeek.com/how-to-flush-dns/
and also try running sfc .scannow command:http://www.howtogeek.com/howto/windows-vista/verify-the-integrity-of-windows-vista-system-files/http://www.howtogeek.com/howto/windows-vista/verify-the-integrity-of-windows-vista-system-files/