My widescreen TV has suddenly fell victim to green and purple patches at the 4 corners and edges of the screen.
Could anyone suggest possible reasons for this.

do you have any non- shielded speakers near the screen?
If so, move them away ASAP.

Ive moved 2 hi-fi speakers which were behind the TV (about 2 feet away), I hope this does the trick. As a bit of knowledge for me, do unshielded speakers affect televisions only when both TV and hi-fi are on , when one of them are on or even when both are off. Thanks.

It's the magnets in the speakers which are still there when the hi-fi is off.

Should the picture go back to normal right away. I've left the TV off just now just in case. Is that necessary or can I turn it back on and it will be back to normal with no permanent damage?

I'm sorry if I sound like a total idiot but I simply dont want any damage to my TV and I know you guys can give me the right info on the matter.

Thanks

this picture SHOULD go back but not always. magnetic fields can permanently shift electron guns in the TV causing distorted colors. it shouldnt matter whether you keep your tv on or off to fix it, just make sure you either get shielded speakers or keep them a few feet away.