Can you reach the website if you enter the IP-Adress instead of the name of the website?

First thing:

How to Flush DNS in Microsoft Windows

In Microsoft Windows, you can use the command ipconfig /flushdns to flush the DNS resolver cache:

C:\>ipconfig /flushdns

Windows IP Configuration

Successfully flushed the DNS Resolver Cache.

You can also use the command ipconfig /displaydns to view the DNS resolver cache.

Second:

type tracert www.united.com and see if your PC can trace the route to the server


Third:

Do you have any firewall/URL-filtering software installed? Maybe for some reason United.com got into the block list.

Last thing: When your problem is solved please edit the thread title.