Forum editpost.php 404 error
 

I'm getting 404 errors when replying to posts in my 4.03 forum.

Strange thing is it doesn't happen every time.

The forum is in a folder named forum, with Wordpress in the
root directory, and the URL editpost.php?do=updatepost&p=1991
(for example) triggers a 404, which Wordpress handles.

Any ideas why this is happening?

Very frustrating when people reply to a post and get a 404.