After rebooting a Windows server, the QlikView services do not automatically start and have to be manually restarted.
This might happen if the QlikView Services go up before Windows has completed starting up all its essential functions.
Resolution:
Ensure that QlikView Services are set to start in "Automatic (Delayed Start)" mode, and not just "Automatic".
This is achieved by running the Services.msc console and changing the Startup type for every QlikView service.