I had the same problem too, sorta. My images worked in the admin cp, but not in quiz.php
I just opened quiz.php, searched for every instance of:
PHP Code:
$vboptions[bburl]}/images
And replaced it with:
PHP Code:
$vboptions[bburl]}/forums/images
It seemed to do the trick.
(I also checked my vBulletin Options to make sure the path was set correctly, and it was, so I don't know why it didn't work.)
Anyhow, that code modification fixed it.