404 errors & The URI you submitted has disallowed characters. on non CI pages

[eluser]Scott Boyde[/eluser]
I am getting quite a lot of these messages on my forum (vbulletin) and some other non CI pages.

Not sure what the cause of this is but I thought I would has in case some one else has came across.

One thing I thought it might be is my .htaccess but not sure.

Code:

#--- DH-PHP handlers ---
#AddHandler php-cgi .php
#Action php-cgi /cgi-bin/dispatch.cgi

#AddHandler fastcgi-script fcg fcgi fpl
#AddHandler php-fastcgi .php
#Action php-fastcgi /cgi-bin/dispatch.fcgi<IfModule mod_rewrite.c>

# Customized error messages.
ErrorDocument 404 /index.php

# Set the default handler.
DirectoryIndex index.php

# Various rewrite rules.
<IfModule mod_rewrite.c>
  RewriteEngine on
  RewriteCond $1 !^(index\.php|forum|leaguestats|predictionleague|robots\.txt|favicon\.ico|license.txt)
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ index.php/$1 [L,QSA]
</IfModule>