Ugh. I'm experiencing new problems today on my i7,256gb. Once again, when the SP3 is just sitting with no programs running, live tiles all off, at 1% CPU usage and cool with no fan----I let it sit doing nothing for 5 minutes and all of the sudden the fan comes on and the unit is hot. In looking at processes in task manager, the system process is what is peaking the system to 40-50%CPU and 99-100%disk activity. A few other process pop up with it when it happens: System Host installer, system interrupts, windows module installer worker, service host: disk defragmenter. All of those pop in and out while the system process is what takes the majority. As soon as I move the cursor by touching screen, touchpad, or keyboard the system process goes to 0% and the system cools. What is going on???????? I let it run for about 15 minutes but was afraid the system was going to overheat so stopped it. Is it defragmenting my disk? Does the system auto defrag the disk? It seems like that is what it is doing as I'm monitoring it now Service Host: Disk Defragmentor is going from 5-20%Cpu usage. I'm gonna let it run til it stops, but yet another thing to add to the list of things that are making our fans blaze up.