Might be that youve had a portable device (FAT32)-external harddrive connected and you deleted something directly off of it that was previously from a Windows-system... In that case you ned to connect the External to a Windows-machine and delete the files from it then and then put it back into the Macbook Pro and then the files from Trash should be gone.
I had this problem for 3 days, didnt know what to do, I called Apple support, they couldnt help me, so I called a friend and he just told me to do that and it worked flawlessly.
Hope you find a solution