Javascript Not Functioning At All on Drupal 7
Check that in html jquery.js and drupal.js correctly open - just click on links in firefox html source view, it's should open js files.
Check your jquery.js and drupal.js in misc folder, if files exists, compare with drupal archive. 
Check how many jquery-VERSIONS.js files attached in html, possibly conflicts can be there.
Check your html source for embedded js scripts (viruses like it).