Today’s problem is a small one with an easy fix. The mystery is what causes it in the first place.

The symptom occurs when trying to open a folder in List View. The problem was that double-clicking to open the folder did not work. The folder did not open. Nothing happened at all. No error message appeared. Nothing.

When this problem happened to me, it was restricted to one and only one folder. It was an ordinary folder, one that I created myself and that I had permission to open. All other folders on the drive worked fine. Just in case this is relevant, you should know that the folder was a large one, containing more than 13GB of photos.

It gets worse. After the folder fails to open, any further attempted action within the same window (such as clicking to select another item) fails to work as well. It’s as if the Mac is frozen while the cursor is within the window containing the problem folder. Outside the confines of this window, the Mac behaves normally.

The work-around is simple. All you need to do is close the window—such as by clicking its close box. When you return to the window, all will be working again (at least until you try to open the problem folder again).

This odd symptom was restricted to List view. Even in List view, it happened only if I double-clicked the folder (or selected Open from the File menu). If I instead clicked the folder’s disclosure triangle, the folder contents showed up as expected. Similarly, if I shifted to any of the other window views (Icons, Columns, Cover Flow), the folder instantly opened even with a double-click.

As I said, there is an easy and apparently permanent fix: Create a new empty folder. Next, using any method that gets you access to the problem folder’s contents, move the contents to the empty folder. Double-clicking this new folder in List view works—even though it contains the former contents of the problem folder. The now-empty problem folder continues to refuse to open. However, you can deal with this by trashing the folder.

The only question that remains is: What causes this folder quirk to appear? I checked Apple’s Discussions forum and found a couple of threads reporting this symptom—but no one offered a cause. When I checked the drive with Disk First Aid, everything was okay. I examined the folder attributes in Terminal; there was no difference between the problem folder and ones that opened. I deleted the folder’s invisible .DS_Store file; this too had no effect. Still, there is something special about the problem folder: If I use Duplicate to create a copy of the folder, the copy inherits the symptom.

At this point, the cause remains unknown, at least to me. If you think you know what’s behind this bug, send me a message. The first one I receive with the answer will win an “I Helped the Help Desk” mug.