Itunes unable to locate songs previously added to library?

[Ericb410]

Hello,
I tried searching but I couldn't find an answer. It seems that itunes 7, on my IMAC has a habbit of loosing "track" of songs. All the files will always be in the same place, but next to some songs there is the little gray explenation point. When i click the song, it says itunes is unable to find the song, but then once I go to folder the song is right there. It also then deletes the songs off my ipod when it updates. Does anyone know what causes this? how can I fix it?
Thanks

 

[mad jew]

Is iTunes set to manage your song files? Do you keep these files on the boot drive? Do you touch the files in any way other than via iTunes?