Hi,
It sounds like you have lost some hypenation settings in your form, not sure how it hasn't happened to me before. You could try going into File ... Form Properties ... Formatting and click the "Remove All Hypenation", then you should be able to add it back in.
When you select the hypenation options an element is added to the form under the proto node, which you can only see in XML Source view.
<proto>
<field name="designer__defaultHyphenation">
<para>
<hyphenation hyphenate="1" excludeAllCaps="1" excludeInitialCap="1"/>
</para>
</field>
</proto>
This means that any fields that reference these setting can do so via the 'use' attribute (see the para.hypenation element below);
<draw name="Text1" w="114.3mm" h="19.05mm">
<ui>
<textEdit/>
</ui>
<value>
<text>Text</text>
</value>
<font typeface="Myriad Pro"/>
<margin topInset="0.5mm" bottomInset="0.5mm" leftInset="0.5mm" rightInset="0.5mm"/>
<para>
<hyphenation use="designer__defaultHyphenation.para.hyphenation"/>
</para>
</draw>
So it would seem you have 'lost' the bit under the proto node. Maybe you can edit the XML Source and add it back. There is a bit more on this here, http://blogs.adobe.com/lcdesigner/2008/07/hyphenation_under_the_hood_huh.html
I also use a similar technique here, http://cookbooks.adobe.com/post_Adding_Ghost_Text_to_LiveCycle_Designer_form-18436.html
Good luck
Bruce