Thank you kmessinger and Josh for your suggestions, but I'm still unable to solve this problem.
kmessinger- I've deactivated all my plugins, but the error message still appears... and I'm afraid of switching my theme as it will erase any changes/customizations I've made (right?) I'm currently using the Headway theme...
Josh- I don't believe I've modified anything in my header.php file because I don't even fully know what that means.... all I've done is use the basic features of Headway such as add blocks, change fonts, add posts/pages, etc. I don't know what FTP or my host CPanel is.... I host through Go Daddy but that is hosting a site I've made through my iWeb on my Mac. I haven't "gone public" with this headway version yet
I appreciate the help, but I'm afraid I'm so under-educated when it comes to WordPress/Web building, your troubleshooting suggestions are over my head. Anyway you can point be to some step-by-step instructions or "dumb down" your suggestions?