Post by email SQL error

The post by email feature deletes the emails properly and shows the contents of the email (when I run wp-mail.php), but that’s all it does. It doesn’t post anything. It returns these two errors:

WordPress database error: [You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near ‘AND category_id = 1’ at line 1]
SELECT * FROM opp_post2cat WHERE post_id = AND category_id = 1

WordPress database error: [You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near ‘ 1)’ at line 4]
INSERT INTO opp_post2cat (post_id, category_id) VALUES (, 1)

In wp-mail.php line 1 is – “require(dirname(__FILE__) . ‘/wp-config.php’);”
and Line 4 is either a blank line or “$time_difference = get_settings(‘gmt_offset’) * 3600;” which don’t really appear relevant. Obviously it’s a ‘line’ from some other file or I’m missing something. I admittedly know just enough to be dangerous, but I can’t find where the file sets a value for “post_id” and it appears to be trying to post a blank entry to the database for post_id.

Possibly relevant info:
January 1 nightly build and January 16th build
Operating system Linux
Kernel version 2.4.21-27.0.1.ELsmp
Apache version 1.3.33 (Unix)
PHP version 4.3.10
MySQL version 4.0.22-standard-log
cPanel Build 9.9.9-CURRENT 120
cPanel Pro 1.0 (RC2)