NIS 2012 strange behaviour

I have NIS 2012 installed on several computers and on one recently it started to show a strange behaviour.

- Software cannot be installed. The installer starts but never shows on screen. New software can only then be installed after a reboot. I suspect that this has to do with NIS as:

- Cannot disable Antivirus Auto-Protect. NIS goes through the motions but when you check is not disabled. Again it gets fixed by a reboot.

- NIS icon disappears from system tray. Fixed by a reboot.

- Liveupdate fails. Fixed by a reboot.

 

I did try the on-line check and fix but it did not report any problem.

 

Any idea what is wrong and how can I fix this?