You can disable mod_security on your vBulletin installation by adding this to the directory it is installed on:
in the .htacces file add
Code:
<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>
I suggest doing this in the admincp directory only and securing your admincp directory with .htaccess. Although vBulletin is really really good with plugging the "once in a blue moon" security holes they encounter, you can't have too much security. And if you're like me and feel comfortable enough with vBulletin, you can disable mod_security in the forum's directory as well.
:D