benjamingreggsmith,

If you are seeing the explorer.exe using that kind of CPU usage with no open proccesses then you need to see where it is located. If it is found in any place other than the system32 folder then it is probably a virus or worm or some other spyware. This would also explain why you have pop-ups galore.

I suggested that you do a complete system scan and try to see what it is that is being so active in the background!