google “itunes 7 missing files” and you can read all about this wonderful <\srcsm> feature in itunes. (I recently lost 2 purchased TV show episodes).

The following report is an illustration of what not to do if you don’t want your purchased media to suddenly vanish.

1. I was downloading Battlestar galactica from itunes

2. Stopped download, brought laptop home and continued on the (very slow) wireless Livebox network.

3. Connected and mounted my external Lacie Hd, started itunes, continued downloading. In the mean time I switched my music library under iTunes–>Preferences to the external HD (which it usually automatically does in itunes whenever my external is connected).

4. Temporarily viewed first downloaded episode, stopped, then quit itunes.

5. Ejected external HD.

6. Restarted itunes so that my library was reverted back to my laptop HD, tried to watch the first downloaded episode but itunes reported the file not found.

7. Quit itunes, remounted external HD, restared itunes (so that my library was set back to the ext HD again)

8. The first downloaded episode, and third downloaded episodes were not found but several subsequently downloaded episodes were found. Checking the ~/Music/iTunes/iTunes Music/Downloads and ~/Music/iTunes/iTunes Music/TV shows folders revealed that the 2 missing episodes were indeed missing. Spotlight searches turned up nothing.

Many others have reported bugs and odd behavior in itunes 7 since its release.

http://discussions.apple.com/thread.jspa?threadID=595144