earlier today i tried to play back a video just as i normally do, and all it did was show a blue screen. "the tape was rolling" i kept messing with it and it just started working. any ideas? what would cause this.

Dave,
It sounds like a head clog. You could try a DV cleaning tape.

This has happened several times with our Z1u's. It was caused by faulty head alignment and dirty heads. In every occassion a tape cleaner was not enough to get the camera back on track, we had to ship them off for repair. We have also had trouble with tapes coming off track from the heads around loud noises which caused a blue screen in playback Ex. gunshots, airplane noise, explosions. Also was told there is no way to save the footage.