Honda Repair: cold start and hot start problem, electrical portion, cylinder car

Question
I have a 2000 Honda Accord 4 cylinder. Car won't start (sometimes on a cold start,sometimes after a hot start).  The problem started at approximately 105,000 miles. The battery, alternator and spark plugs all checked out fine.  My mechanic thought that the problem might be the distributor cap so he put a new one on and I also had him  change out the timing belt due to the mileage on the car.  Now the car has 115,000 miles and I am still having the same problem.  Any ideas on what it could be?  I thought maybe the timing might be off but my mechanic said that is all controlled by the computer on the car.

Answer
Hes right about the timing. Its going to be one of two things., either it has a bad electrical portion part of the ignition switch or a bad main relay. I'm going to lean more twords the switch though. When its running, wiggle the key around and see if it kills. For the relay its located on the drivers side under the dash up high all the way to the left. Its brown and bolted to the steering hanger. I just posted an answer about how to check it on a previous answer so check there on that. Good Luck!