I'm loading JQuery into my TYPO3 page by :
file20 = fileadmin/templates/myjq.js
you don't want to include JQuery that way; Use
page.includeJSlibs.jquery.external = 1 page.includeJSlibs.jquery = //ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js
Edit Using a URL without a specific protocol (http or https) makes sure the inclusion works on both SSL and non-SSL-sites.