I have an article that I want to publish on my Joomla! site. Every time I click apply or save. I get error 500 - An error has occurred! DB function reports no errors>
I read this other question and saw that you can't post the article since it's confidential. Is it in "plain english", does it have html? Could you provide some more information? Joomla has some plugins that "filter" a lot of content. If you try to write "iframe" or "script" tags in Joomla TinyMCE it's going to be filtered, this is Joomla's way of providing security.
Did you try to disable TinyMCE filters? Go to "Plugin Manager", "Editor - TinyMCE 2.0" and change "Code cleanup" options to test.