Q: iTunes Player randomly looses music locations

Over the past several months, I've notice that iTunes randomly looses music from my library, causing me to have to download content again.  My library is @ 12,000 items, not that big, but I find that I now have to routinely scan my library for the cloud symbol on an album cover, or look for the "!" in my play lists indicating iTunes doesn't know where my tracks are.  *** Apple?