Gremlins in the bedroom ceiling lights

My lights did that too ..... just before the converter died.

Measure the voltage at the fuse panel and see if it goes up and down there when the lights go up and down.

You have a loose connection somewhere, I would do as midnightsadie recommended first, I like to solder my connections and use shrink tubing over the connection. Does it come on with the switch off? if so that could be the problem and I would start there..

take the fixture down, check the cheap wire nuts they put them together with, some viberate loose as you travel.

Loose connection. Start checking at the 12 volt power dist panel. Get an electrical person to help you.