Minecart Crazy on powered rail

I was making a mineshaft and place a powered rail on a powered Rail witch was On.It acted as i was hitting it even as it took off with me in it.I was looking for ore and turned the rail Off it stopped. I dont know why this Was And i think its a glitch No Crash no nothing. Then 1.8 came out it Was not fixed But it was not as laggy. Anyone know bout it.