I'm not an electrician and really don't know much but I have a problem and I would like to see if somebody could help me.

I have a lighting fixture in my kitchen, nothing special, it uses 2 U shaped florescent bulbs. The problem is, it doesn't work reliably. If you turn it on, sometimes it works, sometimes it doesn't. Sometimes you have to wait a while for it to come on, other time it never comes on. I've had electricians come over and fix it. They always replace some black box and it works when they are there, but once they leave, problems start again. It's almost like a ghost. So I don't know what to do. I want to mention that there are 2 switches in the kitchen on opposite sides of the room that operate the fixture - I don't know if this matters.

Please help!