Restart your PC.
Then right-click on the drive containing the Recycler, for example the C: Drive.
Go to Properties, do a Disk-Cleanup. This should eliminate the problem.
If not, try rebooting in safe mode, since the file may somehow be in use by some program - maybe even a virus, which is why I recommend running a scan after all this, or if it still didn't work.
Edit: I am not sure how Vista is mapped, but maybe you could try this tutorial:
http://forums.techguy.org/windows-vi...old-files.html
It's for Windows 7 though, but since 7 looks a bit like Vista, maybe this tutorial shows the correct location where to do a cleanup.