Same error, different cause

"Validation error, please try again. If this error persists, please contact the site administrator."

Ive searched around and this seems to be a common error code, but noone in the forums is seeming to have the same cause.

To understand how im getting this youll have to understand what im trying to do.

So i have 10 different page templates. the editors want to just fill out some forms (text snippets, images, ects) and then i take that data and i load up a template file, populate the template with the user generated data. The outcome is a cleanly generated HTML page that fits perfectly into my drupal header/footer and presto, an editor with no html skill has just made a beautifully styled page.

I take the newly generated html code, and I then try to submit it to the drupal /node/add page, in hopes that drupal thinks that someone just filled out the form on the /node/add page, and pasted in the html.

This works (for a while) but then it suddenly will start popping up "Validation error, please try again. If this error persists, please contact the site administrator."

I have not hacked any of drupals core. I created a page which a bunch of forms which submits to an external php file (outside of drupal) which handles the template generation, and then tries to submit the data back into drupals /node/add page

Heres the weird thing. when i submit, it goes to the /node/add/ page, and it shows the error and populates all of the form fields as desired. but when i hit submit, it still will not let me create the page and throws the same error.

I have gone through POST param by POST param, and removed them/cleared them/altered them, and nothing seems to have an affect on it.

Im thinking that the form field: "form_token" or "form_build_id" are the cause. when i clear those out, it erases all the form data from the page.

Is this a method to prevent this type of data entry???