In the event viewer I find constant (every 5 minutes) error that states :
 " The Bitdefender Desktop Update Service service failed to start due to following error:
 The system cannot find the file specified."
 I have Internet Security 2016, and it doesn't show any issues with an update. Actually, I just checked Update setting in General Settings, and everything is greyed out. I can't check/uncheck automatic update. It doesn't seem to be checked now.
  When I press Update on the main console, nothing happens. I don't know if it downloads in the background, but it doesn't show me anything.