How do I fix my SONY color reaqr video projector, KP-53S70?

My SONY was manufactured in 1999. It began to display the menu screen when attempting to change channels or adjust the volume. It will paly a cable channel but the volume is low and cannot be adjusted. The menu screen pops on anytime we attempt to switch to a video, change channels on regular tv or adjust volume. It did occur after unhooking the Wii console. Attempts were made to rehook the Wii to the tv to get it to work but the results were negative.