Hello

I'm trying to install this wonderful looking package and I keep getting this error when I submit my login info on the setup page:
Fatal error: Fatal error: Call to undefined function: sha1() in /home/httpd/vhosts/xxxx.org/httpdocs/photos/zen/auth_zp.php on line 10
I'm running PHP4.2.2 on RHL9.
I tried switching the sha1 function to md5 (in both places in auth_zp) -- after I do this, I no longer get the error, but nothing happens at all. I click submit, it appears to submit the form, but I'm returned with no apparent action having taken place.
Anyone know if there's a way around this?
Thanks