AJAX - Don't Know What's Going On

Hi Guys - I’ve been working through AJAX examples and tutorials on the web - the examples work well when I try them on the tutorial sites. When they allow me to download the files to play with on my own, I do. After loading them up to my hosting account though they don’t work at all in either IE or Firefox?! I checked the server with phpinfo() and can’t find anything listed as disabled that would cause a problem. Any ideas??

Thank You!!