You have your IDE device's incorrectly configured.
You can not have your TiVo A drive connected as hda ( primary master ).
I suggest that you use the following configuration.
hda is your normal computer's boot drive (Primary Master)
hdb is your CDROM (Primary Slave)
hdc is your TiVo A drive (Secondary Master)
hdd is your TiVo B drive (Secondary Slave) if you are using one.