No data is being shown for a machine in my Control Centre

There are a number of reasons why data is not being recorded. Follow the troubleshooting steps below:

Check proxy/firewall settings (see How do I configure my firewall for Netintelligence Web Filter).
Check that the client is still installed (using Windows Add/Remove Programs).
Check that the Netintelligence process in Windows services is running (using Start menu > Control Panel > Administrative Tools > Services). The service that should be running is:
- Netintelligence Client