Re: NisSrv.exe safe or virus
You dont need to worry about the NisSrv.exe file because it is not a virus but instead it is just a part of Microsoft Security Essentials Network Inspection System. This feature was newly added in the MSE version 2. You will not see that in Windows XP but only on Vista and Windows 7. You can verify that by right clicking on the file and selecting Properties. What ever you have read that it belongs to Norton is absolutely wrong.
Re: NisSrv.exe safe or virus
Even I didnt know about this NisSrv.exe file but after checking out, it seems to be a 64bit based program made by microsoft and it is a safe file for sure. If you have installed more than 2 security programs then it might be conflicting with it because that program might be not made by Microsoft. I have noticed this several times where people install too many antivirus software on one system and each one of those program report everything as a threat.
Re: NisSrv.exe safe or virus
Yes, NisSrv.exe is a safe file and belongs to MSE Network Inspection System driver for Microsoft Security Essentials. This startup entry is installed as a Windows service. If you have any other security programs such as Norton, McAfee, TM, AVG, avast, avira, Malwarebytes Antimalware, etc; then try to remove them completely. All other antivirus programs are detecting it as a false positive because they differ from each other.