I have a HV-32P37, which I suspect is fitted with the same tube. I had similar problems which were caused by a PVR which seemed to affect the picture, giving me a patch on the screen where reds appeared pinkish, but this did come and go.
As I understand, these problems are sometimes caused by the fine shadow mask used in these tubes to get the high resolution - it makes the sets more susceptible to external influences such as magnetic fields generated by other electrical equipment, transformers in power supplies, loudspeakers, etc. Don't forget to consider what equipment is at the other side of the wall against which the TV is sited.
The construction of the walls in your house can also affect the set if, for example, one side of the set is particularly close to a brick or block wall.
Try moving any bits of kit which you have around the TV to see if you can isolate the problem, or even make the colour patch move. If that fails, then the only other thing I can suggest is to try moving the TV...
Hope this helps with your problem!