Norton antivirus problem!

Hello, i have a problem with norton antivirus after installing it on a new desktop system based i5 (haswell) with an intel dh87mc motherboard. When i have installed norton antivirus in this computer with windows 7 sp1 if i try to reboot or shutdown computer the shutdown takes too much time. I can see the shutdown windows screen taken too much time before system shutdown. It only happen when i have norton installed. My bios and all drivers are up to date. The problem occur even performed a clean instalation of windows 7 and reinstalling norton despite having cleared registry and program files.

Also i have contacted with norton support and they unistall norton via remote session and they have done a fresh install of norton. But the issue still persist.

Anyone can give me a guideline about what should i do about this unconfortable issue. Also i have noticed that the system is also unstable when the norton autoprotect is on.

Please help me!!!

Thanks you very much.