After I created a couple of forms recently as a last touch I added both a
header and a footer ( there is no code used for anything).
I then saved the form and tried re-open it. I got an error message from
InfoPath stating it could not create a new blank form. It cannot open the
form. To fix the form call my system administrator.
Under the details, it says that the form definition (.xsf) file cannot be
opened because of an error. The file cannot be validated by the xml schema.

It further states  Element '{http://schema....../solutionDefinition}header'
is unexpected according to content model of parent element
'{http://schemas.Microsoft......../solutionDefinition}printsettings

It then gives  line 525  position 17 <xsf:header>

Can any one tell me 1. What happened? 2. How it can be corrected 3. How to
prevent the problem in the future.

Your help is most appreciated