Norton internet security 2011 makes my system freeze after 15 minutes

I am using Norton Internet Security 2011 on Acer Aspire laptop running Windows 7 Ultimate. 

 

Before installing Norton everything was running fine. After installing Norton I find that my computer freezes after being stood for 15 minutes. The restart button will not work - in act nothing works - and all I can do is turn the power off and restart. Of course I then get the windows message asking me if I wish to start in ordinary windows etc etc. 

 

I have no permanently disabled Norton and everything has returned to normal again. 

 

Is Norton really crap, is is that just hype?. I speak as I find and would really love the program to work, but so far all I have had is total hasle. I'm thinking of going back to WH Smith and asking for a refund and buying Kaspersky instead!

 

Can anyone help??