Umm limit internal recursion error, seems that it has something to do with .htaccess as I was expecting but can't seem to find out why it actually happened. A quick google search shows that the URL rewrite rule may have resulted an infinite loop, but if so this should apply to all users running my script. Wonder why Iris is the only one getting this weird error, did she set up another URL rewrite rule through cpanel?
Btw I came across this article from Wordpress, looks like URL rewrite error does happen to very few clients using such scripts, not sure if it will give a hint on how to fix it:
http://www.tokiwinter.com/avoiding-i...d-mod_fastcgi/