Joomla 1.5 get blank screen when editing articles

I had a client contact me saying that their Joomla (1.5) admin worked fine until they tried to edit an article and then got a blank white screen. What was strange was that the live website was working fine, so I checked out the offending admin section and what seemed to be a blank white screen actually contained some code with the following error:

Warning: require_once(__DIR__/articlesanywhere/articlesanywhere.php)
[function.require-once]: failed to open stream: No such file or directory in
/home/vvvv/public_html/new/plugins/editors-xtd/articlesanywhere.php 
on line 17

Fatal error: require_once() [function.require]: Failed opening required
'__DIR__/articlesanywhere/articlesanywhere.php'
(include_path='.:/usr/lib/php:/usr/local/lib/php') in 
/home/vvvv/public_html/new/plugins/editors-xtd/articlesanywhere.php 
on line 17

The error related to the plugin Articles Anywhere by nonumber, which was using code which only worked with php 5.3 upwards and the server had an older version. So the fix I managed to find was to edit a line of code in the file based in plugins/editors-xtd/articlesanywhere.php

require_once __DIR__ . '/articlesanywhere/articlesanywhere.php';

Change to...

require_once dirname(__FILE__) . '/articlesanywhere/articlesanywhere.php';