I've seen similar posts, but very few answers and mostly guesses. I have a InfoPath 2010 form trying to populate the username, manager, spending limit... it works great in preview mode in the client application but errors out when published and trying to open in a browser.
Using SharePoint 2010, IP 2010. got it to work fine in MOSS.
I've attached a screenshot of the erorr and the form. If there is any other information i can provide, please let me know.