I use a Logitech wireless keyboard and mouse that are several years old. All of a sudden, I couldn't drag and drop anything, including emails, desktop icons, files, etc. When I tried to print something in Word, it said the printer wasn't installed (it was), but the document would print find on that same printer using WordPerfect.
I tried booting in safe mode, but it was no help. When I rebooted, it locked up at the stage where a driver (ClassPNP.sys) was loading. (I was able to get past this logjam by hitting F8 as though I was launching Safe Mode, but stopping as soon as it got past the ClassPHP.sys hangup.) I then tried a restore point and that action failed because it couldn't mount a necessary file. BY THIS TIME I'M REALLY HOT!!!!
I launched a Microsoft troubleshooting video and expanded it to full screen. After realizing it was useless, I reached for the Esc key to get out of full screen mode and realized the key was stuck down. I released it and everything works fine. I tried at least 20 times to make it stick again, but it won't.
So, after throwing away about 2 hours, I'm back to work.

Chas.