The tachometer jumps down everything the bell rings?

I start it and then the bell starts dinging about every 3 seconds. The tachometer jumps down everything the bell rings. When you shut the engine off, it acts like the starter is going out, but then it starts. Sometimes you go out and start it and everything is fine. You might drive it for 2 weeks then the bell will start dinging again as you're driving it. Sometimes it stops and is fine. Oh, and the high beams won't come on when it's dinging. The engine runs fine, either way. No warning lights come on, on the dash.
I just can't figure it out. What is going on with my beloved vehicle?