On my test installation of Moodle 1.6 (tarball from 7 July) I see this error logged:
[client 130.70.132.206] PHP Notice: Undefined property: footer in /var/www/htdocs/moodle/blocks/moodleblock.class.php on line 222, referer: http://ucslx01.ucs.louisiana.edu/moodle/login/index.php
As nearly as I can determine, Moodle is filling in blocks on the front page, and encounters the loancalc block, which doesn't define a footer. When I made this change to blocks/loancalc/block_loancalc.php, the error no longer occurred:
*** block_loancalc.php.orig 2005-08-16 00:56:54.000000000 -0500
--- block_loancalc.php 2006-07-11 14:07:30.000000000 -0500
***************
*** 13,18 ****
--- 13,19 ----
$calc = $CFG->pixpath.'/i/calc.gif';
+ $this->content->footer = '';
$this->content->text = '
<script language="JavaScript">
<!--
--James
ps - will submit a bug report next.