mysql_pconnect: Too many connections error

[agligich]

My application is accessed my many users
So i am running application with persistance connection(mysql_pconnect)
I keep getting php warning: Too many connections and my db server goes down and I have to reboot db server to get application to work

I am running my aplication on Linux platform with Apache/1.3.33 PHP/4.3.11 MySQL/4.1.10a
I set max connections to 500
But the error still keeps appearing

Can anyone suggest anything?
Thanks a lot...