The problem has been solved by changing the DNS back to Verizon's DNS. That was one of the first things I thought of, but everybody said it had nothing to do with the problem. It seemed logical to me that it did, though, and it turns out I was right, or that's how it seems to me. Why people thought it wasn't the issue, I don't know. After all, the error message itself mentioned DNS server not responding.
Thank you again for all the time and energy you put into helping me! If I can return the favor (by giving you a little editing), just let me know.