I've had this problem for the last 6 months also. My switch is cracked and burnt at the same spot. Fuse is fine.
I would like to find a solution to this problem too. I just pick up a new connector and switch, but if it's going to do a the same thing I need to look elsewhere to find the problem.
Question. Do either of you have alarms on your car. i read somewhere that the alarm can cause this short in the switch. When you activate the alarm it flashes the lights and horn, which will eventually cause the short in the headlight switch. I don't know if this is true but, just wanted to pass the info on.
65GTFB, 2000 F-350 SC dually with tons of extras., 69 Boss
71MachI, 96F2504X4 with Banks Power Pack