As for blocked websites, check the "hosts" file.
By default it is located in: %SystemRoot%\System32\drivers\etc %SystemRoot% is an environment variable, often C:\windows
But it is possible that a virus could change the registry value that tcpip.sys uses to locate the host file... HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DataBasePath
In there you will see lines such as this:
The system by default is configured to check this hosts file before bothering to resort to DNS. This has many useful applications, but in your case they've used it to prevent you from updating your system... Which makes me think the virus exploited your unpatched windows machine. Remember to keep up to date. Remove the suspect lines, other than the line I listed this file should be pretty much empty if you haven't applied some "Ad Block"ing software.