. . .from her computer. I asked her if they were telling her to do things (one can’t be too careful, ya know), but no, they seem to be short snippets of conversation from time to time. I’m assuming this is some sort of cross-tone with a phone line, but I’ve never heard of such a thing. She’s on cable, not phone line. Any explanations that make sense?
My amplified external speakers at work catch radio stations if the volume is set to zero or very low. Perhaps something similar to this is happening with her?
This often happens with unshielded audio equipment, like telephones, computer speakers, and stereo equipment. The speaker wires are behaving like radio antenna. When the radio signal gets into an audio amplifier, like in a sound card or in amplified speakers, it gets detected and converted into an audio frequency signal that can be heard through the speakers. The end-result is an unintentional radio receiver. Common solutions to this problem are to use shielded speaker wire or to add RF filters to ends of the speaker wire.
Did she recently install an EVP receiver? 
But seriously – another way this can happen is if you have a Bluetooth adapter on your system. The Bluetooth adapter basicaly acts like a radio transceiver and can pick up conversations from nearby cell phones. I had it happen on my computer about a month ago – my Bluetooth receiver even picked up the caller ID information from the guy’s cell phone. It was the most bizarre thing at the time and if the wife wasn’t sitting here listening to it with me I might have begun to think my skull was leaking. It took a bit to figure out what it was all about, and it’s also useful to note: Bluetooth adapters can pick up bits of broadcasts beyond its normal range of 100m or so.
It could be either of those things. . .if I knew what the heck they were. She doesn’t have any blue teeth. EVP receiver! HAHAHAHAHAHA…huh?
A couple years ago one of my friends got a spyware/virus that dowloaded and played commercials very softly. I guess they were going for some sublimminal thing. It took a hell of a scrubbing with ad-aware, spybot, and about 3 anti virals to get rid of it.
Cheap computer speakers would be my guess. That or very strong CB/radio broadcasts nearby. Are there big rigs going by her computer’s location? We used to pick those up on our TV speaker.
I work near a Naval Air Station and occasionally pick up what seem to be transmissions from passing planes.
My stereo speakers picked up “radio disney” when the stereo was off when I lived in California. It was unshielding wiring, we think.
Another vote for cell phones. I’ve picked up my neighbor’s cell conversations before (though that was a few years ago when cell phones and computers were a little less advanced).