What could be causing this?

This started a couple weeks ago and I can't find out what's causing it.

My laptop has slowed, takes forever to load a page. It also will just stop loading a page, stop a video I'm viewing, the page will go blank, come back on then start to "flash" on and off. Videos will only run a few seconds, stop, load, run a few seconds, etc There is, on occasion, lag time from what I type to when it appears on the screen or it won't appear at all. I can see that the one light on the front of the laptop that shows it's "doing something" is constantly flashing and will go to a solid light, even if I'm doing nothing. Other times the cd/dvd player will start up then shut down with a few seconds. Something must be running in the background but I'll be darned if I can find it. I've run a Malwarebytes scan, SuperAntiSpyware scan Defender full scan and a CCleaner scan and none of them have found anything other than some tracking cookies. I've even gone to the Dell website and run their check program(s) and it says everything is running normal. How can I find whatever it is that's running using up all the memory or whatever it is using and get rid of it? :mad: :mad: :mad: