Errors image loading

After the last update 3.1.0 loading images I get an error http://joxi.ru/brR8x9qTBJoz02 and thumbnails are not created. The message: “Post-processing of the image failed likely because the server is busy or does not have enough resources. Uploading a smaller image may help. Suggested maximum size is 2500 pixels.”
I tryed to increase WP memory limit, but it didn’t help. Only after deactivation of the plugin started to work properly.