Hi,
All the system crashes are at Norton AV and some are related to faulty memroy.
Suggestion
Re-install Norton AV. If it still crashes, execute the following procedure
1. Check the temperature of the CPU and make sure that it is not overheat (ie temperature < 60C)
Make sure that the CPU fan works properly
2. Downclock the ram
3. Clean the dust inside the computer case
4. Make sure that the ram is compatible to the motherboard
5. Check the bios setting about memory timing and make sure that it is on
If it still crashes, diagnostic which memory stick is faulty
1. Take out one memory stick. If windows does not crash, the removed memory stick is faulty.
2. If you have only one memory stick, replace the ram