If you do not either remove the sd card, disable it, or initialize it, you are in for more trouble. If I do not do one of those things, my static ip assignment "works", but it doesn't. It returns from the begin() routine, but malfunctions with any UDP function, like DHCP and NTP.
Here is a sample of the setup function I use to initialize both devices.
edit: This applies to all the ethernet and SD examples in the IDE. AFAIK, none take into account the other device that may be present on the SPI bus.