"hidden program" Startup Defender , don't appear in the list of installed software .

hi everybody ,

 

by some time  I am haunted by a software which qualifies as STARTUP DEFENDER and that often output messages near the notification area asking to authorize NIS live updates ( ! )  by clicking the button 'accept change' as opposite of 'deny change' .

Moreover a countdown flashes in the first button and an unknown standard behavior should follow its expiring .

The program , which I an not completely aware to have downloaded , is accredited in the net to be an ANTI-malware software but no mention I found on its author and its behavior seems to me very suspicious .

WORSE , I can't find any file with that name in my PC , no program installed with that name and no possible candidate with other name in the programs installed in a reasonable lapse of time backwards ! 

Yet NIS complete scan gave negative results such as Windows Security Scanner .

Can someone help me eliminate this soft( mal)-ware ?

Thank everybody 

frenmm.