The fact that some images work tells me that TimThumb is behaving fine. If you go to the broken image url you will see that the error is ‘no mime type specified’ which tells me the issue is with the image rather than the script. I would suggest resaving the image and seeing if that … Read more
Best way: Remove the timthumb script from your server and change your theme so as to not require it in the first place. Timthumb isn’t really necessary with newer versions of WordPress. The add_image_size() function can be used to create custom image sizes in the theme. And most older themes I’ve seen still using it … Read more
Unfortunately at moment Gravatar service itself only accepts single number for size and only serves square images. So you have to achieve it with CSS or download, modify and cache images.
In my opinion the built in <?php add_image_size( $name, $width, $height, $crop ); ?> function is much more flexible, easy and with less overhead. It does resize-crop, so I don’t see a reason to go back to TimThumb (which I used extensively in the past).