Bad Fox reception in one of the DVRs

I'm old school (still waiting for the new TiVo). So, all of my DVRs at home are HR10-250's. For some reason, the one in the living room has been having reception problems with Fox at night. Reception is perfect during the day, but goes bad around 8pm (just when American Idol starts, UGH!) The other three HR10-250's in the house have no problem and recieve Fox's reception perfectly ok, so I know it's not the OTA antenna.

Any thoughts?