So I\'m using the colorbox plugin for a contact form. I am just the default colorbox properties, so it should automatically adjust to the div it contains (right?).
Well
I've investigated the problem.
Try to see which content you load by ajax. If it has some images without "height" and "width" attributes, the scroll bars can appear.
It happens because the browser does not know about the image's size and doesn't wait until it loads to calculate the page layout. After the first load the image is in the cache and the browser can calculate the size.
Try to specify the size for you images. For me it works.