nrf24l01 radios + RF24 library + Ethernet shield do not work together

Using Arduino Networking, Protocols, and Devices
2

Try your RF24 library with the ethernet shield connected, but disabled. Add this to your setup() function:

void setup() {
    // disable SD SPI
    pinMode(4, OUTPUT);
    digitalWrite(4, HIGH);

    // disable w5100 SPI
    pinMode(10, OUTPUT);
    digitalWrite(10, HIGH);

    // now do the rest of your setup
}

Does the RF24 work when you try that?

BTW, both those devices use a significant amount of 5v. Careful about your power supply. The onboard regulator may have trouble with both.

edit: Do not use D10 on the nrf24 device. That is the slave select for the w5100.