losing permission to songs in my library
In the past three weeks, I have been losing permission to songs in my library. I can locate the song in my ITunes library and the folder where they are stored, but the songs that I have lost permission to have "green ink". I have moved them out of ITunes and tried to reload them, but ITunes will not allow me. These are songs I purchased on other websites and uploaded to my ITunes library. Some of the songs I have had for years and have been able to play them all along. But recently, certain songs in my library I lose permissions for.
Also--I only notice it is happening when I click play on a specific song and the player skips the song. I go back and keep trying to click on it and it won't play. Then when I go into library, I find that it now has "green ink" and I have lost permissions.
Help
iPod (5th generation), Windows 7