You might be able to PM one of the Cox authorized people who might know if something like that happened in your market.
Other options... see if you can swap your DCT2500 for another one at the office.
It could be the cable, it could be the DCT2500 and it could be the TiVo. A solder joint could have disconnected anywhere in the chain and it would stop working. There should be a way to connect a PC (if it has a serial port
)to the DCT2500 and fake the change channel commands.
tivocommunity.com has a forum for series 2 users that's still fairly active, you might find information there. I really don't know.