Coincdentally, I updated to NIS 22.5.0.124 this week and also upgraded to a Premium Malwarebytes user.
Since then I have discovered thro several experiments that Malwarebytes is blocking NIS Liveupdates on Windows Vista.
In Windows 7 there is no problem.
In Malwarebytes Settings - Advanced Settings - unclick "Start MalwareBytes with Windows" and reboot. This at least allows you to do a NIS Liveupdate before you want to start Malwarebytes