Can't move desktop icons... sometimes
Here's an odd one. I am using a Macbook Pro Retina and the newest rev of Mountain Lion.
I have only two icons on my entire desktop: the Macintosh HD icon, and a folder named "Attachments". Picture them stacked vertically, with Macintosh HD on top.
If I click and drag the mouse from the top-down to select the two icons (so drag over the Macintosh HD and then the Attachments Folder), then try to move them, they won't move. I get the little grey "no" indicator and they just drop back where they were after I let off the mouse.
If I click and drag in reverse - that is, I drag over the Attachments Folder first, and then Macintosh HD, and then try to move them, they move compliantly to wherever I drag them to.
Now, if I rearrange the icons, no matter how I arrange them, if I drag across the HD first in pursuit of marking both icons, they will not move. If I drag first across the folder, and then the HD, they move just fine.
Any thoughts on this?
MacBook Pro with Retina display, OS X Mountain Lion (10.8.2)