JVC Camcorder Distorted Playback

Hi,
i bought a jvc camcorder new about 12 months ago and i have had playback problems since december 2007. the problem is, i record things absolutely fine, but when i switch to play mode and play back what i recorded, the image is there, but there are big purple horizontal lines going across the image, distorting it.

i have tried putting a new tape in and trying it on that, but it does exactly the same thing. Also, i have uploaded the videos onto my computer and the green lines still come up. I need to know, is it the type of dv tape i'm using (jvc mini dv 60), or is it a problem with the camcorder playback function? If so, what would i have to do to fix it?

I have attached a photo.

Thanks for your help, Matt.