Doesn't matter how long you have had it mate. It could have been lying on a shelf and knocked about for years before you bought it.
I bought a regular Saffire last year, and it broke within 1 day. Was getting absolutely nothing out the outputs at all. Took it back to the shop I got it, and they gave me a new one which I took home and it worked straight away. Not had a problem since - touch wood.
Does your Saffire model have the Saffire control panel thing?
Can you even get Winamp or Media player or anything to play through it?