goodmans tv?

Hello, hope someone can help, i have a goodmans tv, model no ..... GTV69W2DT. i conect my xbox 360 to this tv,but the last time i used it after i turn off xbox, my tv as a problem with colour, the colour all messed up, but after a few days it rights itself and all fine, but i used the xbox again the other day, and same thing happened when i turn xbox off, any ideas, thank you for reading hope you can help....
David