Well, I have read all the threads you showed me.

I found the problem is really serious.

And you were advised to install some other softwares.

When the pop ups happend, press ctrl+shift+esc together. On the task manager, click "task", and watch which task remaining more CPU resources. If it was an unusual task you do not know, just try to terminate it.

As I mentioned, you've tried to login to the safe mode, but nothing was changed when you switched to the normal mode. My suggestion, you could try to download an other free anti-virus software for temporary use. Because I think your McAfee is insufficient to fix your system.

Still, safe mode is always the best enviroment to solve safety problems.

If you do not enjoy solving this problem, I also suggest you to restore your important data to another storage device, format your computer C drive, and re-install a new system. It is the simplest way and it could avoid the 'sequelae' of virus either.

Hope that help!