Q: I keep getting: "there was a problem downloading x, an unknown error occurred (-50) " - how do I fix it?

I keep getting: "there was a problem downloading x, an unknown error occurred (-50) " or another one about file corruption when trying to get the available download from the season pass I have been fully charged for. I have turned comp off and on, am connected to steady internet, have the latest version of itunes, and have tried re-downloading several times. What next?