To all using Internet Explorer:
I knew in the back of my head why it was that you were all seeing grey backgrounds on the images displayed in custom profiles. There's a problem with IE in which it can't display alpha transparency from 24-Bit .png (portable network graphic) files.
As [
this] website shows you, there's a fix for this, in which you embed JavaScript or PHP directly onto the page with the images. We're not able to do that though, since we can only customize our profiles via CSS.
In order for our profiles to be fully compatible, we'll either have to save our images as 8-Bit .png files, or .gif files. Both of those will work with IE's transparency problems, yet both file types also have a limitation of 256 colors per file.
The profile disigners need to deal with grey blocks instead of transparency, or deal with only 256 colors, so our profiles can be compatible with all browsers.