Is anyone able to help me understand why iTunes seems to randomly remove music from my albums? This is my set-up:

1. All iTunes music stored on eHDD
2. All hard-copy, purchased albums are imported via iTunes
3. Stream iTunes music to my MBP

Just opened my Doors collection. All the albums are there, but some songs are just no longer in my playlist. For example, songs 1, 3, and 7 from an album. I then have to click Add to Library and find those three files from the eHDD and reimport them. So, they are still there, but just not on the playlist. Doesn't sound too bad, but sure isn't fun with nearly 40 GB of music and randomly disappeared music. When I am getting my groove on and mentally amped for the upcoming song that fails to appear it is such a deflating experience.

I haven't changed anything in my set-up for about a year.