We have 3 (near identical) Sitecore sites on a development server and 2 out of the 3 fail to resize the images using the inbuilt Sitecore query string parameters.
The media image is returned but it fails to resize the image.
So far I've tried file permissions,
config diff (web.config and showconfig.aspx) but nothing obvious stands out.
I'm thinking its something in IIS but cannot think what.