Maya,
The first thing I want you to do, is sign-in to Apple Support Communities. Now, in the last message you posted, look at the bottom of the post, if 'Edit' is there, click,edit, then remove the Serial Number from the next to last line you copied.
Now, on to your Trash can problem.
Please control+mouse click on an empty spot on your desktop create a new folder. You can leave it as 'untitled folder' or name it something like 'items to trash'.
Now control+mouse click on the Trash can in the dock to open the trash. Move all the items in the trash can into the folder you created. Then close the Trash can window.
Open the folder you created, and move one item to the trash. Then empty the trash. Do this for each item. If a item will not empty from the trash, remove it from the Trash can like earlier, and place it in another new folder titled 'items that won't trash'.
After all the items that can be trashed are trashed, open the folder that contains the items that won't trash.
Then post the name or names of the items that won't empty from the trash, just to make certain there is nothing that you're trying to trash, that you shouldn't be trashing.
Good luck.