We're using Krea Content Elements (http://www.krea.com/content-elements) on a new site and have discovered that if a standard EE validation issue fires, (i.e. a required field missing content) that on the subsequent page load the content you had added to your Content Elements field is lost! Bit of a showstopper... anyone aware of a resolution to this, in fact can anyone reproduce?
I'm not able to reproduce on CE 1.6.5 at least. Tried saving an entry w/o a Title and then had some content in a Heading and WYSIWIG field in a Content Elements field - hit submit and was redirected back with the content intact.
If you're able to reproduce consistently on a clean install I'd say report a bug.