I decided to start over from scratch because I could not get by the Error 500 message.
So I created new databases and installed just the newest versions of WordPress and vBulletin. No mods or plugins have been added. I created a single user in vBulletin named Integration - ID is 2.
I've created no new categories and so am just using the default category which is ID 2.
The forum url is
http://nameofmysite.com/forum
The relative path is /forum
I've turned on the plugin
The site uses UTF-8
Auto-Integrate is NOT turned on.
Post articles to forum is turned on.
Excert from post is turned off.
When I try to write the test post, I see the drop-down box with the correct 'Main Forum' category and when I click Publish I get Error 500.
Does anyone have a suggestion or would someone be willing to login to my site at 1and1 and look at my setup? I can PM you the login info.