Let's get some additional information ...
What vehicle are we discussing?
How many lights are we discussing - standard high beam/low beam headlamps PLUS a set of driving/fog lamps?
Are we discussing driving lights or fog lights?
How many problems are you describing?
I see only one cause for concern - the low beam lights do not always work - as JR has pointed out, that is possibly a problem with the combination switch, I will also add a possible burned or intermittent contact in a wiring harness connector.
It's not unusual for driving/fog lights to be switched with the low beams, in fact, it is a legal requirement in some countries - fog lights can only be used with low beams, driving lights can only be used with high beams.