Since about four days ago, every time I restart or reboot my Windows 7 machine, the system comes back up with Microsoft Security Essentials disabled. The network and sharing icon in the status bar appears with the teal-colored ring over it.
Entering the Network and Sharing Center from the icon takes extra time, but when it appears, there is nothing in the active networks list. This is ironic, because testing the network by pulling up websites in Chrome works just fine.
Next, I tried to start CPU-Z, which requires UAC elevation. I started it from an icon on the desktop, which caused the pointer to get a teal ring on it. At that point, Windows Explorer and all the desktop icons stopped responding.
I tried another elevated app from the Start button app list. Same result, only that time the Start button UI stopped responding.
So, I tried Task Manager, through the ctrl-alt-del mechanism, which worked, but clicking on "Show processes from all users" resulted in the same behavior: Task Manager UI stopped responding altogether, including not permitting the UI to move around on the screen though I was able to start other TM instances. Curiously, the "frozen" TM still updated its list of running processes.
10 minutes after trying all this, all the UAC prompts I expected appeared, the status bar changed to report that MSE and the network were working fine, and everything seemed to return to normal.
What could be going on?