Delete errant iTunes entries

I have a few podcasts that just won't die. The podcast files are long gone but for some reason I cannot get my iTunes library to recognize that. There are 8 podcasts that show up on my second gen AppleTV. I created a smart playlist that lists all podcasts and sure enough all 8 show up there. They have the standard exclamation point because none of the files can be found. How can I get rid of these entries?

I have tried editing the library xml file but the itl file keeps adding them back everytime I reopen iTunes.