I noticed that the trash sounds (putting a file in the trash, emptying the trash) will randomly stop working. A restart usually fixes this but at some point it will randomly stop working again.
Open the Finder. From the Finder menu bar click Go > Go To Folder
Type or copy / paste: ~/Library/Preferences
Click Go then move the com.apple.dock.plist file from the Preferences folder to the Trash.
See if that made a difference...
Ack, I clicked the wrong button. This did not solve my question.
As I said in my original post, I already deleted the Dock preferences (I'm not sure if you were posting in the wrong thread)
The same thing happens to me, even with the 10.8.2 update, it's still an issue.
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