Commented Unassigned: Cannot download - Proxy error [25666]

I'm unable to download...it says something about a proxy authentication error in the details.
Comments: ** Comment from web user: bdeem **

__Work Around / Fix__

Change your defaultProxy to use the default credentials (your NTLM login).

Edit %windir%\Microsoft.NET\Framework\v4.0.30319\config\machine.config

Add the defaultProxy element shown below, ie

```
<configuration>
...

<system.net>
<defaultProxy enabled="true" useDefaultCredentials="true"/>
</system.net>

...
</configuration>
```

[<defaultProxy> Element (Network Settings)](https://msdn.microsoft.com/en-us/library/kd3cf2ex.aspx)

> __useDefaultCredentials__
Specifies whether the default credentials for this host are used to access the web proxy. The default value is false.