Background tasks freezes computer running W7-64

I am having a constant issue of having my W7-64 freeze while norton 360 premier edition executes backgroud tasks. It is the inability to execute any other thing with the comoputer. Mose stays on, hard drive is continuouslky running, but I cannot do anything else. 

Windows promotes a forced shutdown (unexpected).

This started a few weeks ago, but it is now persistent.

Anyone knows what should I do?