It has intermittent problems with starting?

I bought my car used, and ever since I've had it, it has intermittent problems with starting. Since I've had it the starter has been replaced twice, the relay was replaced, spark plugs replaced, wires replaced, and its been checked for oil leaks (which it doesn't have problems with). Despite all of this it continues to have problems starting. Every three or four months the problem starts small. I'll go to start the car and the dash board lights will turn on, but the engine won't turn over. It doesn't make any noises like its trying to turn over, just the lights turn on and thats it. I'll turn the key multiple times and it will finally start. In the beginning it will only take a couple of tries to start it but the longer I let the problem go the longer it takes to start and can end up taking hours to start. Like I said its been in the shop multiple times for this and a grab bag of things have been changed. The strange thing is (and mind you I don't know anything about cars) I feel like it may be electrical because I've had issues with parking brake lights coming on for no reason, the interior dash lights not working for a couple of hours, the power windows not working some times. All of those problems will however correct themselves within a few hours to a couple of days. Please if you have any advice I'd really appreciate it.