When RC is installed on Apache without mod_php (I'm using phpsuxec), the php configurations in the .htaccess file cause 500 server errors.
The .htaccess file should check for mod_php before trying to configure it:
<IfModule mod_php.c>
php_flag display_errors Off
php_flag log_errors On
php_value error_log logs/errors
php_value upload_max_filesize 2M
</IfModule>
You should also include a php.ini file (in the same directory) that sets the same configurations for phpsuexec installations:
display_errors=off
log_errors=on
error_log=logs/errors
upload_max_filesize=2M
it works on mine fine with and i run phpsuexec,
i got 500 errors when having problems with zend and ioncube config even on scripts that didnt require them, have you been playing with their settings recently?