Video cameras problems?

I have a white line running through the picture on playback and the sound is muffled, on another tape I can't hear the sound at all - but I did a year ago. On other tapes, everything's fine?

Just to build on what Andrei has already said,

All brands (within the same price range) are so simullar that its more about who will you want to stay with for the long run and less about the spec. For example, if you buy a Nikon camera now then you will obviously buy Nikon lenses. That means if you want to upgrade your body to a pro camera then you will have to consider that you have a whole tonne of Nikon lenses ("So why would I buy a Canon body").

There are a few subtle differences, however. Canon are a lot more restrained when they build their cameras. Believe it or not there's a point where Megapixels and focal lengths become a problem. Canon's cameras may seem lower spec than their Nikon counterparts but that is for a reason. Nikon crams all the megapixels they can into their sensors because they believe image quality, in terms of resolution and ppi is more important that functionality and ease of use. More megapixels means there's more chance of anti aliasing in the image and also much worse low light sensitivity because the more megapixels there are the more light is needed to light each pixel. So under controlled situations Nikon images can be a lot more crisp and detailed. However Canon cameras have less trouble taking their photos because there are less issues caused by a bloated sensor.

Now I'm a bit of a Canon fanboy, I will admit it. However, i have no problem saying that Nikon cameras take fantastic images, especially portraits. I will re-iterate that All brands (Canon, Nikon, Sony, Panasonic) are very similar at this price range. Its about personal preference and your goal with photography or video going into the future.