can't send email - php fatal error

[dj3plet]

[16-Jul-2007 07:03:19] PHP Fatal error: Only variables can be passed by reference in C:\htdocs\webmail\mail\program\steps\mail\sendmail.inc on line 336

this is the error i've been getting recently. i was able to send emails until recently. i just restarted my server to see if it was just some sort of weird glitch with PHP but that didn't work.


My setup, if it helps:
RC-rc1
hMailServer
Apache2
PHP5
XP