I have it in a php script, on my desktop, the script is running fine.
But on my laptop, and other desktop (not the one I used to develop the script), when tried to run the script, got the problem: Fatal Error, call to undefined function session_is_registered() (or sth like that, I don't remember word by word)
And my host supports php4

And it's pretty weird since php is server-side, and there shouldn't be any problem with client-side!!!
Anybody has any idea about this?