plugin giving 404 after recent core update

Hi there. I have written a plugin that uses a short code to put a multi-step registration form on a WordPress page. It is a series of forms that each have a hidden “action” variable that is posted with the form to the plugin script that is basically a giant switch statement on $_REQUEST[‘action’].

Up until a recent wordpress update, this was working fine.. now suddenly when I submit the form I get the wordpress 404 page. The url is correct, and refreshing the page starts the process over again at the default (first) page – it’s just not triggering the next form like it used to. In the inspector in chrome, I can see the post variables that are should be there.. it’s just triggering the 404 instead of the proper page.

I don’t know exactly which version this broke on as the form isn’t used much, but I would guess the 3.3 upgrade. Does anyone know if there were any changes made to the core that would affect the $_REQUEST object within the scope of my short code function?

Anyone else have this issue? anyone have any ideas how to go about trouble shooting this?

Cheers,

whiteatom