Multi-step form process + validation

[eluser]Crucial[/eluser]
On an application I'm working on, I use a lot of form "wizards," or forms that have multiple steps to them. I'm using the validation class as well.

I'm trying to come up with the best way to go through a multi-step form like this, but am running into some problems.

The first step will show no errors because nothing's been posted, but every step after will also show the validation errors on the top of the page because there's still $_POST data avaiable from the previous form.

I can clear the $_POST data out and store it in flashdata, but that removes the validation process and you can just continue on through the forms without ever giving an error.

I know the way I have this setup is wrong, but have been banging my head against the wall on this and need a fresh set of eyes.

I don't want the URL to change either, it's always going to the same place.

If you need to see the code I have I'll post.