Do I have a dice unit?

Today when I was warming my car up, the cd I was listening to stopped playing, I noticed the display said "detached", then changed to "usb". The radio is the stock head unit. When I tried searching for what could be wrong, one of the search results was an old archive of the dice forums.

I bought the car from a dealer second hand, and I was not told of any stereo upgrades. The car is a 2001 330ci.

Can someone point me in the right direction? Do I have a dice unit hidden somewhere? If so where should I look?