Lightroom :: 4.3 - How To Delete Pictures Using Contextual Menu Or Delete Key

I have LR 4.3, Camera Raw 7.3

Until yesterday I was able to delete pictures, using the contextual menu or the delete key. I got the message asking me if I wanted to delete them from disk or from the catalog.

But now, that popup message doesn't appear. The picture is not removed, just nothing happens.
 
I checked the logs and this is the error message:
 
performCommandDesc could not perform command ag.library.expandAllStacks (Command was disabled.).
 
I uninstalled LR moving it to the trash. Then I deleted the com.adobe.Lightroom4.plist and I also removed the folder ~/Library/Application Support/Adobe/Lightroom.

I rebbooted the machine and installed it again. But the issue is still there, with the same error message.
 
I verified the disk and checked file permissions.

I also tried to use another catalog from a backup.
 
Nothing, same error.
 
One anusual thing that I did before the error was to install the "HDRsoft Merge to 32-bit HDR Plug-in for Lightroom - Version 1.0"

I removed it but the error was still there. After the re-install I didnd't install that plug-in again so if it was the problem, it shouldn't be after the clean installation that I did again.
  
Machine Specs:
Man mini server mid 2011
2GHz Intel core i7
Ram: 8G
Graphics: Intel HD Graphics 3000 512MB
OSX: 10.8.2 (12C60)