It sounds like a php error was occurring causing the issue.
It would probably show the error if you view source of the page, or if error reporting is turned off, it can be turned on by adding the following code at line 1:
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
?>
when pasting from word, you need to use the Paste From Word Toolbar option in HTML editor, it is the button with the picture of a clipboard and the "W" word logo over it.
Word uses non standard markup that can cause issues when pasting into an HTML page.