NSS version 21.6.0.32 a few silly questions from a NEWBIE

I had to do a complete system restore using my USB recovery drive last month. It seems one of the Windows partitions failed. Everything appears to be fine now. Since I was starting fresh I choose to install NSS that's free from Comcast. It was almost time to pay for my other AV program so why not switch?     In my Norton Tasks tab the Windows Registry Cleaner has never been run, just want to know this is safe to run.  Sorry I got a little ahead of my self. I have a Gateway NE56R41u laptop running Windows 8.1  64 bit.  I have an Administrator account and a User account. From my User account it looks like almost all items under the "SETTINGS TAB" must be set from my Administrative account. Under SETTINGS there is an ADMINISTRATIVE SETTINGS section, anything you can tell me about this section will be appreciated.  I did read the User Manual from a Comcast provided link.  ftp://ftp.symantec.com/public/english_us_canada/products/norton_security_suite/manuals/nss_ug.pdf

I have to say it is not a well written or informative guide. Just trying to be honest not critical. I have read in some older forum posts that Malwarebytes Anti-Malware (I have the paid version) and Norton do not play well together. IS THIS STILL TRUE?

Here is my last item is about my CPU. It is a Intel B960 dual core, I have 8 GB RAM (2 x 4 GB DDR3), a 500 GB Internal Hard Drive & an External 1 TB Hard Drive.

Under TASKS when I Run Diagnostic Report one item has an Orange Exclamation Point stating my CPU is SLOW and recommends I replace the CPU, Under the PERFORMANCE Tab I can check my CPU USAGE over the past week.  There are two peaks 1) while burning a disc CPU is at 69%  2) CPU at 49% (Chrome 42% - MBAM 7%) neither peak lasts for very long and to me the CPU does not seem slow in any way.

We are talking about a laptop I paid $320 for brand new, I can not see spending $100 to $150 plus labor to replace the CPU.