First thing to check - is this definitely a TiVo? If you're not sure, check here - it's only worth checking because some of the later advice will potentially differ and many people get the TiVo & V6 confused.
Most importantly at this stage - are these picture problems affecting live TV? Recorded programmes? OnDemand?
The 3 types of programmes are handled differently within the box, and would all be caused by different things.
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