@kemical: Well, Norton is still awesome IMHO, Ross.
I still use it on my main Laptop, and my son's Win8.1 Lenovo PC. I've tested it thoroughly on W10 Home; not so much on W10 Pro. Though that shouldn't make a difference. I completely agree with you (when do I not?) about uninstalling it for troubleshooting. We also agree that OP should remove the Norton and run Windows Defender for purposes of troubleshooting his multiple problems. There are also a number of important
UPGRADES and UPDATES that should be done once the problem is resolved and the Norton is reinstalled. This is especially true if your Norton license (any product) was dated 2015 or before.
And with the 3 external drives he has *it's difficult to tell from OP posts if they are all 4 internal drives, or some are and some are connected via USB*--I don't think he understands there's a significant difference in how the drives are physically connected to the Motherboard!
@silverman: Thanks very much for posting back that correction on your hard drives in Post #124 for us! Nice job.
kemical is going to continue working through your issues;
but hopefully the statement you made about having much or even all of your personal data files on that C: bootdrive (the OCZ Vertex 250GB SSD drive) without having them backed up elsewhere onto external media, such as your other 3 hard drives or to the Cloud somewhere!! This means that our operation is going to be a much higher risk of potential data loss. And we'll have to be very much more careful on what repair options we provide to you.
Can you answer that backup question for us when you get a moment, please?? If you
DO have most or all of your files backed up elsewhere than that C: bootdrive, we can suggest more aggressive repairs. kemical, holdum, and the rest of us all proceed carefully in every case, but this is certainly information we need to know. Thanks!!
I only jumped in since your screenshots and posts indicated that you had multiple secondary hard drives hooked up and you were locked into a
SAFE MODE situation and couldn't get out. We've seen this several times before on W10 machines since last year. kemical has got the lead on this one and he knows what he's doing. If you haven't made provisions for proper backup of your files as discussed above, we're sorry you are running into a deadline getting it fixed, but hey this help is free. If you have system critical files and programs you need to get ASAP--like tomorrow; you should consider taking it in to a licensed computer repair Technician and paying money to get it done!
How much money is it worth to you to get it fixed immediately?? At many reputable repair shops, they also offer a
RUSH charge when someone has an emergency such as you do. Best Buy Geek Squad & MicroCenter both offter these. However, from your posts, it appears you are in UK, is that right? Then perhaps a similar shop over there.
Good luck & we'll be following your thread hoping for some good news.
<<<BBJ>>> 
I've tested this extensively the last 3 years with Vista and have done some preliminary testing with W10. 
<<<
Wake up!
