Downloads Folder takes 20 minutes to load

There are several old threads about similar problems, none of the solutions are helpful for me.

I recently formatted and re-installed Windows. Everything worked fine for a couple weeks. Suddenly my downloads folder is maddeningly slow - it actually takes about 5 minutes to load (I said 20 in the Title because that's how it was before the re-format).

A few days ago it loaded almost instantly, I can't have downloaded more than a few files since then, so volume of files in the folder is not the issue.

I checked the folder properties - it's still optimized for "general"

Some older threads suggested my antivirus software might be the culprit. I'm using Microsoft Security Essentials. I may try uninstalling it to see if that helps anything.

This has happened, BTW, on almost every Windows 7 computer I've worked on, so I'm sure it's not an uncommon problem. However I suspect it's not the same problem experienced by people who complain about the folder taking 10-15 seconds to load...

Any ideas?

Now here's a strange thing. Shortly after I posted this I noticed my keyboard was responding slowly. So I re-booted.

Now my Downloads folder loads instantly.

Sorry to be crying wolf - it was like a deja vu of the kinds of problems I was having before I reformatted, but maybe it was just a temporary glitch. I'll post back if it happens again.