I would say that it is caused by magnetic fields near the tv ie speakers beside the tv. I suggest you try unplugging the tv, leave it unplugged for several hours (overnight) and then plug it back in in the morning and hopefully the problem will be resolved. I had the same problem on a Panasonic and did that to fix the problem. Good luck.

The problem sounds very much like a magnetic problem, just as the other poster described. However, leaving the television unplugged for a period rarely fixes this problem. The television may have a "degauss" feature built in - this should be used first. Magnetic fields warp the image produced by the CRT guns. If a magnetic field remains close to the television tube for long enough, it can cause permanent damage. If you have anything with a magnetic field - particularly audio speakers - move them away and see if the image is affected. Some speakers are not adequately shielded, even if they claim they are. Items with an appreciable steel or iron content can become partially magnetized and can produce such effects. If removing anything containing a magnetic field or steel from the vicinity of the television has no effect and you do not have a degauss feature or it does not sove the problem, you may need to have it degaussed by a technician and then have the guns realigned. It is also possible that this problem is caused by a problem within the television: either the guns have drifted out of alignment or there is a circuit fault that has thrown them out of alignment. This would need to be addressed by a technician.

I had the same problem on a 32inch 100hrz model 32ZD08B 4years old cost £900 and find that the tube is gone and cost estimate is £200 plus It is fitted with a tube made by Philips . So is it worth paying extra for a brand name or by cheap and through it away once broke?.

probably magnetic......it could even be caused by magnets 6 feet away so if moving things away doesn't work it needs replacing......

We need to see a picture of the problem, but sounds like either an issue with magnetism built up as others have stated or could be purity magnets out of position on the neck of the tube. Call a local TV servicer.