I have a vBulletin board that I manage and while recently had users complain about the Quick Reply not working. They had to go into the advanced editor to make it work.
Two days later another user complained about not being able to update their profile. While debugging this, both problems became very clear.
I had recently put in some rewrite rules to make the forum more SEO friendly. However there are a couple situations where the rewrite rules broke down. I was missing the two lines colored in green below.
RewriteRule ^/videos.html /forums/36-Bowling-Videos-amp-Pictures
RewriteRule ^/threads/ckeditor.php /ckeditor.php?t=$1 [L]
RewriteRule ^/threads/(.*) /showthread.php?t=$1 [L]
RewriteRule ^/forums/(.*) /forumdisplay.php?$1 [L]
RewriteRule ^/entries/(.*) /entry.php?$1 [L]
RewriteRule ^/blogs/(.*) /blog.php?$1 [L]
RewriteRule ^/members/ajax.php /ajax.php?$1 [L]
RewriteRule ^/members/(.*) /member.php?$1 [L]
RewriteRule ^/list/(.*) /list.php?$1 [L]
RewriteRule ^/list/author/(.*) /list.php?$1 [L]
RewriteRule ^/$ http://www.bowlingboards.com/forum.php [R,L]
It was that simple. I am sure I am missing some other rules, and will try to get them corrected in due time.