Here's some more stuff I tried.
I noticed that there was no rp_users table. So I copied the table from Classifieds. And while at it I copied the class_usergroups table to rp_usergroups as well. Still no go.
I still get
Warning: mysql_fetch_row(): supplied argument is not a valid MySQL result resource in /home/www/tdpri.com/reviewpost/forums/phpbb2.php on line 353
And it won't give me access to Admin (doesn't show option)
Then I deleted all my cookies.
But I still get the same errors on the reviewpost index page. Now it showed me logged out after deleting the cookies. But it wouldn't let me log in.
I logged in on my main phpbb website and went to reviewpost. Now it shows me logged in, but still not admin.
Looking at the rp_usergroups table in phpmyadmin it shows me as having cpaccess.
Looking forward to hearing some solutions from you about all of this.