ITunes is trying to synch a track which is no longer in my Library

Question

A couple of weeks ago, iTunes had a problem adding one particular track to my iPod. It has had similar problems before - generally solved by creating a new MP3 of the file (within iTunes) and deleting the old one. This time, however, that didn't work. Nor did creating a new copy with another application and replacing the offending file. What's more, iTunes continued to throw me an error notice related to this file even when I excluded it from the iPod folder I use for synching. At this point I removed the file from my iTunes library (no great loss, actually). So I was pretty bemused to find that iTunes continues to tell me that it can't synch this one file every time I synch my iPod.
I've confirmed that the file is not in the Library, and there is no copy on the iPod itself. My question is, how do I make it stop doing this (short of a scorched earth wipe and restore of the iPod, which would take hours, and might not help, if the problem is somewhere in the iTunes library). It seems to me that the name of the file must be held somewhere on a list in my iTunes files, and can be simply edited out. But where?

Answer 1

Backup drive?
Subscribe to iTunes Match?
If neither of the above and you don't have the CD and can't find your tracks on the computer then they you're stuck.  A file recovery utility will cost $100, plus another $100 for an external drive to which to resue the files, and may not even work.  You can buy a lot of CDs for $200.