How can i get my tv to stop automatically changing...

Question

when the tv is turned on the normal picture stays for a few seconds then automatically switches to the menu sreen. pressing the menu button returns the screen to the normal picture, but only for a second. the sound is not affected, and channels can be changed with remote for dish receiver. pressing the menu button continually gets the picture back. sometimes menu button needs to be pressed for 10 to 15 minutes.