100% CPU usage after Windows update

About a month ago my HP laptop began running very slow when I played any type of video. When i looked the CPU was at 100%. This could be a dvd, netflix, utube, flash, media player. It would continue to run slow after any of these applications were closed. If I restarted or let it go into sleep mode it would operate fine until I started a video of some sort. Ran every virus and malware program under the sun and no problems found. To rule out a hardware issue I restored the laptop to "out of box" state. Initially everything seemed fine. I played a dvd for 45 minutes and it was fine CPU never went about 10%. Satisfied that my virus was gone i started doing the windows updates. Tried to play a video last night and the CPU usage is back to 100% when i put in a dvd.
HP dv7, i7, 8gb RAM.

Hello redbaron 91 and welcome to Seven Forums.

Did you use Task Manager > Processes tab to learn that CPU usage was at 100%? Which process was hogging the CPU?

Returning a computer to out of box condition won't necessarily rule out a hardware issue. Your RAM may not be seated properly. Your graphics card may have problems.

Yes, when I look at task manager whatever was running at 1-2% prior to running a video is running at 20% after playing a video. I restart or close the lid for 10 minutes and everything goes back to 1%. No other new processes show up in task manager after the problem occurs. My RAM never goes above 20% in use. It seems odd that it worked until I did the windows update.
Thanks for your help.

One other thing, if i add up the CPU % from task manager per process it doesnt add up to the 100% cpu usage reading

To get a more accurate understanding of how your computer's resources are being used, open Resource Monitor.

Resource Monitor

Since the problem seems to have started around the last time you did Windows Updates, I'd uninstall them and see if the problem corrects itself.

Windows Update - Uninstall an Update

When you decide to reinstall the updates, I'd do it manually. Turn off automatic updates. Depending on how many updates you have to install, do them in groups of no more than 3 - 5 at a time. Keep track of the KB numbers for each group. Install the first group, reboot. If no problems are noted, install the next group, reboot. If problems are noted, you'll know exactly which group to uninstall. Then try reinstalling one at a time and rebooting after each install. They'll either all install OK or you'll know which is the problem update. Leave it for last. Yes, it's a lot slower this way but it gives a better update experience with fewer problems.

Well, I did some research this weekend and found the following. I formatted to "out of box" again and noticed the problem instantly without updating anything. Sometimes I would hit 100% cpu usage opening a web browser or once just opening resource manager did it. So I began watching my CPU meters and core temp. The problem starts when the core temps reach 138F and up and the CPU clocks down to 80 mhz from 2000 mhz. Memory usage nevers goes above 20% of the 8 gb and the graphics card hasnt moved above 1%. Although I dont think it does anything unless you play a game. I think I have a cooling issue.