I'm having this issue on two computers, both MacBooks with Mavericks. I have large external drives, one Seagate, one WD. I use them as scratch folders, so when I get through doing what I'm doing, I want to delete the contents. In Finder, I select the folders and select the Trash can. On the desktop I select the trash can and enter Empty Trash. Emptying the trash seems to launch properly, however it is very slow. (Defining very slow as has not changed the number of items remaining - 11,494 -- in 15 minutes).
On the one computer I got frustrated. I selected the X (stop) on the Trash thing, and it said it was stopping. After half an hour, I tried to get out of it--could not. Forced shut down with the power button. On restart, the external drive would not mount. Disk Utility cannot fix it.
Now in the same place on another computer.
MacBook Pro with Retina display, iOS 6.1.4, 13" Late 2012