The QlikView .Net Web Services may consume all memory on the server eventually crashing the entire server.
The issue appears to be caused by Windows Defender locking the QlikView ProgramData/Application Data related service files. The consequence is the .Net Web Services may build up the log entries in memory instead of saving them to disk.
For more information on Windows defender see https://technet.microsoft.com/en-us/windows-server-docs/security/windows-defender/windows-defender-overview-windows-server
The .Net Web Services are:
Directory Service Connector
Web Server Service (QlikView Web Server or IIS/Settings services)
1. Open the settings for Windows defender (type settings in the search and select “Update and Security”)
2. Exclude the folder c:\ProgramData\QlikTech from windows defender.By clicking on the "exclude a folder" button and browse to the folder.
3. It may be necessary in some instances to disable the Active Scanning feature as well or configure the Service exceptions as well.