Make sure your ownerships on all files and folders are correct ....
(Should be setup for the new account login on the new server)
Also, is your public_html folder permissions itself correct?
Code:
OWNER: (account login)
GROUP: nobody
PERMISSON: 750
Also, is the original server and new server both running the same PHP?
If the original server was SuPHP or FCGI and the new server just DSO then you could have problems accessing your scripts as well unless you do a lot of permission modifications likely needed.