Before doing any other more drastic measures just posted, try just disconnecting the USB for up to 4 hours. (It may only take 20 minutes or so -- monitor the GC date to see when it updates.) This works for me and there's no sense suffering all the other hassle if this relatively simple thing works. On my TiVo HD setup, with no splitter separating TA and TiVo inputs, I still can watch the non-SDV channels while the USB is disconnected. I've only had this happen oh maybe once a year or so, but if it was happening more often I would put my TA on a lamp timer.