multiple unidentifiable strings in registry & other

In my registry under CLSID, there are what looks like hundreds of unidentifiable strings ,some repeats: trouble is, from time to time there are these myriads of files and other times only a handful: it also looks as if someone is regularly getting on my computer (I have Win 8), because the entry image screen before my login screen shows the default Win 8 screen instead of my custom pre login screen. I am including an image of part of what I see:

Can you suggest what may be going on?