My laptop is an Acer Aspire V3-571 running Windows 8.1.On switching on,sometimes NIS 2015 doesn't work.The only way I can get it to work is to switch off and back on again.Sometimes I have to do this a few times.Another way is I run NPE which doesn't find any problems but NIS will then launch.I have tried Norton Remove and Reinstall but I still have this intermittent problem.Can anyone tell me what is wrong and how to rectify.I did the live chat thing and they removed and reinstalled it but the problem persists.Any help would be great.