In Disk Utility (and I almost never recommend this since I feel that it is over recommended) try repair disk permissions and then repairing the disk.
i still can't empty mine.
unfortunately, i dont have a windows, or linux install on here.
i tries sudo -s them rm -rf /Volumes/931gb/.Trashes
i tried downloading 3rd party, force empty trash apps.
i tried control apple key shift backspace.
only thing i didnt try is repair disk permissions because i dont want to ruin my ntfs drive
im using paragon