when you add a plugin to a page, it uses a document relative path to the plugin page:
$WA_aboutus_1300209542461 = new WA_Include("aboutus.php");
if you move the page that is calling the plugin page to another directory, you need to adjust this path.
lets say for example sake that I have a folder in the root of my site called test. In ths folder, i have the files index.php and aboutus.php
i add aboutus.php as a plugin to the test.php page. the code to attach the aboutus.php file will look like the code above.
If i now move the index.php file to the root of the site, I need to adjust the path to the about us file:
$WA_aboutus_1300209542461 = new WA_Include("test/aboutus.php");