Menus cause white screen of death!

I am in a bind.

I'm using Joomla 1.5 and the hot_business template. I've used this template on other sites, so I know it works. Here's how the problem started:

I used the template and customized it by changing the CSS files. The only thing that I changed in the index.php file is that I added a link to an additional CSS file and some Google Fonts.

After working on the template on the live site for 2+ weeks, the front end turned into the white screen of death. After some trial and error, I discovered that the top menu and a menu in the footer that were causing it. When I disabled them, the site came back.

After I turned on the debugging I got this:

Fatal error: Non-static method (null)::/var/www/vhosts/heritagechurchofgod.org/httpdocs/templates/hot_business2/html/mod_mainmenu/default.php() cannot be called statically in /var/www/vhosts/heritagechurchofgod.org/httpdocs/libraries/joomla/utilities/simplexml.php on line 607

After a lot of frustration, I removed the altered template and installed the unaltered version of hot_business until I could figure it out.

Today, that template began behaving the same way.

Help?

The website is www.heritagechurchofgod.org

You turned off your menu.

Can you send us code part of file where error is reported.

Also if that is fresh hosting simplexml requires additional component , so maybe that is missing:

see this:
php.net/manual/en/simplexml.installation.php

I have turned the menus back on and now they are working in the default template.

When I tried to locate the error above, this is what I found:

function map($callback, $args=array())
{
$callback($this, $args);
// Map to all children
if ($n = count($this->_children)) {
for($i=0;$i<$n;$i++)
{
$this->_children[$i]->map($callback, $args);
}
}
}

This began at line 605 not 607 like the error stated.

I think you need to install/enable simplexml for PHP. Ask your hosting administrator for help

see this:
php.net/manual/en/simplexml.installation.php