Image with large file size not cropping

By default, WordPress uses the GD Graphics Library to resize and crop images. On servers with limited resources however, GD fails on images with large file sizes.

If you really need to keep the size of your images, but want to keep your file sizes down, consider processing your images first with tinypng.com. Their online compressor retains as much quality as possible, processes up to 20 files at a time, and is free.