The structure of the form was as follows:
<table......>
<form action="/support/kb/indexcfm/fuseaction/single/id/1117/somepage.html" method="post">
<tr><td></td></tr>
</form>
</table>
The proper structure is to enclose the table tag within the form tag....
<form action="/support/kb/indexcfm/fuseaction/single/id/1117/somepage.html" method="post">
<table......>
<tr><td></td></tr>
</table>
</form>
ActivEdit walks the DOM after loading to discover the form it's enclosed in and remembers it to post the form after it moves the current content of the editor to a hidden textarea, do cleanup and listen for api instructions when the onSubmit callback is called. The improper nesting caused ActivEdit to get lost.
If the form is nested properly, it's possible that Safari was installed without the JRE 1.4.2. Use System Update to install the latest JRE.