I have resolved this issue.
It apparently had something to do with the onFocus event of the <body> tag. Perhaps your control does not like to have the form it is on sent to a JavaScript function?
At any rate, I retooled the document so that this function is no longer necessary. I removed the onFocus event from the <body> tag, as well as the <script> tag link to my .js file, and the JavaScript error went away.
You might want to look into why your control behaves this way.
Thank you for your time.
James