It took me a couple of days to realize it was actually only happening in one particular folder, where I had tons of pictures which I've downloaded from the net.
Thinking it might be due to the number of files, I created some sub-folders in another directory, and slowly separated them into catagories (like film clips, movie trailers, bizzare, etc). It was a long process, because I could only transfer a few files at a time before Windows Explorer wanted to shut down again.
I ran across some old movie clips which no longer seemed to want to run on my computer, no matter what program I opened, and no matter that all my programs have the latest updates and drivers. So, I deleted those.
I just finished moving all the files a few minutes ago, and everything seems to be working fine. I never did find out what was causing the problem.