Give it 24-48 hours. There is a lot going on in the background when you install a new box (programming downloads, etc.), so it will be slower while that is going on.
The series 3 TiVo has the same behavior if you want native resolution from the DVR. I put up with the blanking to get native resolution to the best converter in the stream. It is probably not the DVR. I had expensive converters in line when I used the Series 3. At least the Series 3 was a THX certified unit and did have quite good conversion. I don't think that is going to be true for he HR22 base platform in the THR22.Thank you! Once I changed the resolution setting, things got better. Just a quick gray screen before the channel locks it.