ok, heres the deal, i have never heard of this happening, but lets see this here
open a terminal and run (i assume you are running gnome)
cd ~/.gnome-desktop
then
rm Trash
then open a text editor and type (exactly, this is important)
Code:
[Desktop Entry]
Version=1.0
Encoding=UTF-8
Name=Trash
Type=X-nautilus-trash
URL=trash:
X-Nautilus-Icon=gnome-fs-trash-empty
this should return your trash icon to its normal operation