Annoying whine from TV - not Nancy Grace...

[toxcrusadr]

Help me help me. I have digital cable with a cable box I've had for some time. Being a cheapskate I split the output and run a cable down to the basement so I can watch while I'm working in the shop without renting a second box. We're still on low def, since the basement TV is a big '93 Mitsubishi, so I didn't ask them to reset my box for hi def or anything when we got a new flatscreen upstairs last winter. All of a sudden the downstairs TV developed a high pitched whine - I would say in the 3000-5000 Hz range, hard to say for sure - it does change with volume, so maybe it's the TV itself. Just wondering if anyone has ever had this happen as a result of running a cable like that.