This is pretty weird. With no change in anything on my OS disk (I keep data separate) today, I was unable to open Windows Explorer- it would display the drive tree on the left and then just hang. Every time. I used all the ways I know to open it, they all did the same. I waited at least five minutes and they never responded. So I fell back to another OS drive from 5 months ago, and it did the same. Disconnected all peripherals, and it did the same. On a whim, I Explored the Recycle Bin and everything responded normally, I could access the complete display. Everything else seems to be fine, and I am virus-free.
Now when I open Explorer again (Win-key-E or My Computer) it does the same- only after a few minutes the right pane comes back with all the folders. Like it has to warm up. Or sometimes not, right now it did the same and I had to force it closed. I live in Explorer, as long as I found the other way in it's no big deal, but it sure seems odd.