Video Asylum: Tivo problems by thur

Hello, I write to see if anyone has experience with Phillips tivo units. I own the 6000 model and have had problems with recorded movies. Recorded movies have excessive pixilation, stuttering (video skips and stutters), and dropouts (movie stops playing and Tivo box turns off and restarts). This only seems to happen with recorded shows longer than one hour. This occurs on clear days when weather is not an issue with reception. The tivo support staff person suspects it is a problem with the hard drive. Has anyone else had a similar experience? It seems as if the hard drive is shot. If that is the case, rather than repairing a unit that cost me 99 USD, I am considering purchasing a new unit. Does anyone have experience with the phillips 240080 (series 2) unit or the Sony SVR 3000? The sony has an intriguing feature that allows four levels of recording quality.
Thanks all
Arthur