Thanks for the suggestions. I just realized that ONE file from the Scritaculous source files (effects.js) was being loaded. I'm still using some of those effects on my old Prototype pages. The problem I'm having is most likely associated with this file.
Are there any known conflicts between jQuery 1.2.6 and Scriptaculous (when using jQuery.noConflict())? Version of the effects.js file: 1.8.1 (latest)