Maybe not? It was all too much fun at the office one day on a similar complaint. Sure enough, the PC was playing a radio station but no software was installed to do that. We shut down the PC and the radio kept going. It was the cubicle next door with a radio in the right spot... Nobody was home there, but the alarm clock was waking up and playing.

1. Shut down next time to be sure it's the PC.
2. Fans that are failing make odd noises.
3. Modems can pickup radio signals...

Bob