First of all, I know (re: my WP version). I do all updates for my network on Fridays, so that my child site admins know when to look for possible wakiness from newly incompatible plugins.
So...I'm trying to get a theme (Pure3) that uses timthumb.php to work on my child sites, but it's not generating the thumbnails into the cache folder like it's supposed to (folder is empty). I've set the cache folder and timthumb.php files to several different permissions to no avail. I've contacted my host, and PHP-GD is active, so I know that's not the issue. Now i'm reading that the URL for images in a multisite child site is virtual, which causes the issue.
There seem to be lots of tuts online for solving this problem when the theme has timthumb.php looking for the image in a custom field, but the theme I'm using has it looking for the "featured image" for each post. I'm not coming up with any solution for this particular situation (multisite + featured post). Anyone have ideas?