We've got an InfoPath floating around that was created in InfoPath 2010. It has been distributed to a handful of users through a SharePoint document library - unfortunately users with InfoPath 2007 aren't able to submit the form, or even open it. They receive the error message: "The form template was created with a newer version of InfoPath. This form template was created by InfoPath version 14.0.0."
Has anyone else encountered this problem? Is there a known procedure for converting .xsn files from version 14.0.0 to a version compatible with InfoPath 2007?
To open the form in InfoPath 2007, you will need to set the form's compatibility to InfoPath 2007. You can do so in the Form Options dialog. If you have used any newer features such as the People Picker, it may downgrade your user experience and force you to recreate some of these controls.
If you do not need some of the more advanced features of the InfoPath client, you may consider having your users access the form using the Web Browser interface. You can set this as the default open mode for the document library, or you can put "?OpenIn=Browser" in the URL when you open the form. See details on Microsoft's site about using query string parameters for Web-enabled forms.