If this is an Uno, you can't use D10-13 for LEDS when using the SPI. The ethernet shield uses the SPI bus for both the w5100 and uSD. Use other pins.
If this is an Uno, you can't use D10-13 for LEDS when using the SPI. The ethernet shield uses the SPI bus for both the w5100 and uSD. Use other pins.